DISCLOSURE UNDER RULE 2.10(C) OF THE TAKEOVER CODE

NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION IN WHOLE OR IN PART, IN, INTO OR FROM ANY JURISDICTION WHERE TO DO SO WOULD CONSTITUTE A VIOLATION OF THE RELEVANT LAWS OF SUCH JURISDICTION

THIS ANNOUNCEMENT CONTAINS INSIDE INFORMATION

FOR IMMEDIATE RELEASE

30 September 2022

RECOMMENDED CASH ACQUISITION

of

RPS Group plc

by Tetra Tech UK Holdings Limited

a wholly-owned subsidiary of Tetra Tech, Inc.

to be effected by means of a scheme of arrangement under Part 26 of the Companies Act 2006

DISCLOSURE UNDER RULE 2.10(C) OF THE TAKEOVER CODE

Update on the non-binding Letter of Intent given by RWC Asset Management LLP

On 23 September 2022, the boards of Tetra Tech, Inc., Tetra Tech UK Holdings Limited ("Tetra Tech") and RPS Group plc ("RPS") announced that they had reached agreement on the terms of a recommended cash acquisition pursuant to which Tetra Tech (a wholly-owned subsidiary of Tetra Tech, Inc.) will acquire the entire issued and to be issued share capital of RPS (the "Acquisition"), to be implemented by means of a Court-sanctioned scheme of arrangement under Part 26 of the Companies Act 2006 (the "Scheme") (the "Rule 2.7 Announcement").

Capitalised terms used in this announcement, unless otherwise defined, shall have the meanings given to them in the Rule 2.7 Announcement.

As set out in the Rule 2.7 Announcement, Tetra Tech had received a non-binding letter of intent from RWC Asset Management LLP ("RWC") indicating their intent to support the Acquisition by way of the Scheme, in respect of a total of 16,106,118 RPS Shares, representing approximately 5.80 per cent of RPS' issued share capital on 22 September 2022 (being the latest practicable date prior to the Rule 2.7 Announcement).

RWC has advised Tetra Tech that it has since disposed of 6,000,000 RPS Shares.

As a result, with effect from such disposal, the non-binding letter of intent given to Tetra Tech by RWC to support the Acquisition has ceased to apply in respect of the RPS Shares so disposed of by RWC.

The non-binding letter of intent from RWC is now therefore given in respect of its remaining holding of 10,106,118 RPS Shares, representing approximately 3.64 per cent of RPS' issued share capital on 30 September 2022.

The person responsible for arranging the release of this announcement on behalf of Tetra Tech is BofA Securities.

Enquiries:

Tetra Tech + 1 626 470 2844

Jim Wu, Investor Relations

BofA Securities (Financial Adviser to Tetra Tech, Inc. and Tetra Tech) +44 20 7628 1000

Edward Peel

Geoff Iles

Tom Brown

Important Notices

Merrill Lynch International ("BofA Securities"), a subsidiary of Bank of America Corporation, which is authorised by the Prudential Regulation Authority and regulated by the Financial Conduct Authority and the Prudential Regulation Authority in the United Kingdom, is acting exclusively for Tetra Tech, Inc. and Tetra Tech in connection with the matters set out in this announcement and for no one else and will not be responsible to anyone other than Tetra Tech, Inc. and Tetra Tech for providing the protections afforded to its clients or for providing advice in relation to the subject matter of this announcement or any other matters referred to in this announcement. Neither BofA Securities, nor any of its affiliates, owes or accepts any duty, liability or responsibility whatsoever (whether direct or indirect, whether in contract, in tort, under statute or otherwise) to any person who is not a client of BofA Securities in connection with this announcement, any statement contained herein or otherwise.

Further Information

This announcement is for information purposes only and is not intended to and does not constitute an offer to sell or an invitation to purchase any securities or the solicitation of an offer to buy any securities, pursuant to the Acquisition or otherwise.

The Acquisition will be made solely through and on the terms set out in the Scheme Document (or, if the Acquisition is implemented by way of a Takeover Offer, any document by which the Takeover Offer is made) which, together with the Forms of Proxy (or forms of acceptance), will contain the full terms and conditions of the Acquisition, including details of how to vote in respect of the Acquisition. Any decision in respect of, or other response to, the Acquisition should be made only on the basis of the information contained in the Scheme Document or any document by which the Acquisition is made.

This announcement has been prepared for the purpose of complying with English and Welsh law and the Code and the information disclosed may not be the same as that which would have been disclosed if this announcement had been prepared in accordance with the laws of jurisdictions outside England and Wales.

In accordance with normal UK practice, Tetra Tech or its nominees, or its brokers (acting as agents), may from time to time make certain purchases of, or arrangements to purchase RPS Shares, other than pursuant to the Acquisition, until the date the Scheme (or the Takeover Offer, if applicable) becomes effective, lapses or is otherwise withdrawn. These purchases may occur either in the open market at prevailing prices or in private transactions at negotiated prices. Any information about such purchases will be disclosed as required in the UK and will be reported to a regulatory information service.

RPS and Tetra Tech will prepare the Scheme Document to be distributed to RPS Shareholders. RPS and Tetra Tech urge RPS Shareholders to read the Scheme Document when it becomes available because it will contain important information relating to the Acquisition.

This announcement is not an advertisement and does not constitute a prospectus or prospectus equivalent document.

Overseas Shareholders

The release, publication or distribution of this announcement in or into certain jurisdictions other than the United Kingdom may be restricted by law. Persons who are not resident in the United Kingdom or who are subject to other jurisdictions should inform themselves of, and observe, any applicable requirements.

Unless otherwise determined by Tetra Tech or required by the Code, and permitted by applicable law and regulation, the Acquisition will not be made available, directly or indirectly, in, into or from a Restricted Jurisdiction where to do so would violate the laws in that jurisdiction and no person may vote in favour of the Acquisition by any such use, means, instrumentality or form (including, without limitation, facsimile, email or other electronic transmission, telex or telephone) of interstate or foreign commerce of, or any facility of a national, state or other securities exchange of, any Restricted Jurisdiction or any other jurisdiction if to do so would constitute a violation of the laws of that jurisdiction. Accordingly, copies of this announcement and all documents relating to the Acquisition are not being, and must not be, directly or indirectly, mailed or otherwise forwarded, distributed or sent in, into or from a Restricted Jurisdiction where to do so would violate the laws in that jurisdiction, and persons receiving this announcement and all documents relating to the Acquisition (including custodians, nominees and trustees) must not mail or otherwise distribute or send them in, into or from such jurisdictions where to do so would violate the laws in that jurisdiction. To the fullest extent permitted by applicable law, the companies and persons involved in the Acquisition disclaim any responsibility or liability for the violation of such restrictions by any person.

The availability of the Acquisition to RPS Shareholders who are not resident in the United Kingdom may be affected by the laws of the relevant jurisdictions in which they are resident. Persons who are not resident in the United Kingdom should inform themselves of, and observe, any applicable requirements.

The Acquisition shall be subject to the applicable requirements of the Code, the Panel, the London Stock Exchange and the Financial Conduct Authority.

Additional information for US investors

RPS Shareholders in the United States should note that the Acquisition relates to shares of an English company and is proposed to be effected by means of a scheme of arrangement provided for under, and governed by, the laws of England and Wales. A transaction effected by means of a scheme of arrangement is not subject to the tender offer rules or the proxy solicitation rules under the US Exchange Act.

Accordingly, the Acquisition is subject to the disclosure and procedural requirements applicable in the United Kingdom to schemes of arrangement which differ from the disclosure requirements of United States tender offer and proxy solicitation rules.

This announcement does not constitute or form a part of any offer to sell or issue, or any solicitation of any offer to purchase, subscribe for or otherwise acquire, any securities in the United States. Neither the US Securities and Exchange Commission nor any US state securities commission has approved or disapproved or passed judgment upon the fairness or the merits of the Acquisition or determined if this announcement is adequate, accurate or complete. Any representation to the contrary is a criminal offence in the US.

However, if Tetra Tech were to elect to implement the Acquisition by means of a Takeover Offer, such Takeover Offer shall be made in compliance with all applicable United States laws and regulations, including any applicable exemptions under the US Exchange Act, including Section 14(e) of the US Exchange Act and Regulation 14E thereunder. Such a takeover would be made in the United States by Tetra Tech and no one else.

In the event that the Acquisition is implemented by way of a Takeover Offer, in accordance with normal United Kingdom practice and pursuant to Rule 14e-5(b) of the US Exchange Act, Tetra Tech or its nominees, or its brokers (acting as agents), may from time to time make certain purchases of, or arrangements to purchase, shares or other securities of RPS outside the US, other than pursuant to such Takeover Offer, during the period in which such Takeover Offer would remain open for acceptance. These purchases may occur either in the open market at prevailing prices or in private transactions at negotiated prices. If such purchases or arrangements to purchase were to be made they would be made outside the United States and would comply with applicable law, including the US Exchange Act. Any information about such purchases or arrangements to purchase shall be disclosed as required in the UK, shall be reported to a Regulatory Information Service and shall be available on the London Stock Exchange website at www.londonstockexchange.com.

Each RPS Shareholder is urged to consult their independent professional adviser immediately regarding the tax consequences of the Acquisition applicable to them, including under applicable United States state and local, as well as overseas and other, tax laws.

Financial information relating to RPS and/or the RPS Group included in this announcement and the Scheme Document has been or shall have been prepared in accordance with accounting standards applicable in the United Kingdom and may not be comparable to financial information of US companies or companies whose financial statements are prepared in accordance with generally accepted accounting principles in the United States.

RPS is organised under the laws of England and Wales. Some or all of the officers and directors of RPS may be residents of countries other than the United States. In addition, most of the assets of RPS are located outside the United States. As a result, it may be difficult for US shareholders of RPS to effect service of process within the United States upon RPS or their respective officers or directors or to enforce against them a judgment of a US court predicated upon the federal or state securities laws of the United States. It may also be difficult to compel RPS and its affiliates to subject themselves to the jurisdiction and judgment of a US court. .

No profit forecasts or estimates

No statement in this announcement is intended as a profit forecast or estimate for any period and no statement in this announcement should be interpreted to mean that earnings or earnings per share for Tetra Tech or RPS, as appropriate, for the current or future financial years would necessarily match or exceed the historical published earnings or earnings per share for Tetra Tech or RPS, as appropriate.

Disclosure requirements of the Code

Under Rule 8.3(a) of the Code, any person who is interested in 1 per cent. or more of any class of relevant securities of an offeree company or of any securities exchange offeror (being any offeror other than an offeror in respect of which it has been announced that its offer is, or is likely to be, solely in cash) must make an Opening Position Disclosure following the commencement of the offer period and, if later, following the announcement in which any securities exchange offeror is first identified. An Opening Position Disclosure must contain details of the person's interests and short positions in, and rights to subscribe for, any relevant securities of each of (i) the offeree company and (ii) any securities exchange offeror(s). An Opening Position Disclosure by a person to whom Rule 8.3(a) applies must be made by no later than 3.30 p.m. (London time) on the 10th business day following the commencement of the offer period and, if appropriate, by no later than 3.30 p.m. (London time) on the 10th business day following the announcement in which any securities exchange offeror is first identified. Relevant persons who deal in the relevant securities of the offeree company or of a securities exchange offeror prior to the deadline for making an Opening Position Disclosure must instead make a Dealing Disclosure.

Under Rule 8.3(b) of the Code, any person who is, or becomes, interested in 1 per cent. or more of any class of relevant securities of the offeree company or of any securities exchange offeror must make a Dealing Disclosure if the person deals in any relevant securities of the offeree company or of any securities exchange offeror. A Dealing Disclosure must contain details of the dealing concerned and of the person's interests and short positions in, and rights to subscribe for, any relevant securities of each of (i) the offeree company and (ii) any securities exchange offeror(s), save to the extent that these details have previously been disclosed under Rule 8. A Dealing Disclosure by a person to whom Rule 8.3(b) applies must be made by no later than 3.30 p.m. (London time) on the business day following the date of the relevant dealing.

If two or more persons act together pursuant to an agreement or understanding, whether formal or informal, to acquire or control an interest in relevant securities of an offeree company or a securities exchange offeror, they shall be deemed to be a single person for the purpose of Rule 8.3.

Opening Position Disclosures must also be made by the offeree company and by any offeror and Dealing Disclosures must also be made by the offeree company, by any offeror and by any persons acting in concert with any of them (see Rules 8.1, 8.2 and 8.4).

Details of the offeree and offeror companies in respect of whose relevant securities Opening Position Disclosures and Dealing Disclosures must be made can be found in the Disclosure Table on the Panel's website at http://www.thetakeoverpanel.org.uk/, including details of the number of relevant securities in issue, when the offer period commenced and when any offeror was first identified. You should contact the Panel's Market Surveillance Unit on +44 (0) 20 7638 0129 if you are in any doubt as to whether you are required to make an Opening Position Disclosure or a Dealing Disclosure.

Electronic communications

Please be aware that addresses, electronic addresses and certain information provided by RPS Shareholders, persons with information rights, participants in the RPS Share Plans and other relevant persons for the receipt of communications from RPS may be provided to Tetra Tech during the Offer Period as requested under Section 4 of Appendix 4 of the Code to comply with Rule 2.11(c) of the Code.

Publication on website and availability of hard copies

A copy of this announcement will be made available (subject to certain restrictions relating to persons resident in Restricted Jurisdictions) on Tetra Tech's and RPS' websites at https://www.tetratech.com/investor-offer and https://www.rpsgroup.com/tetra-tech-offer, respectively. For the avoidance of doubt, the contents of these websites are not incorporated into and do not form part of this announcement.

RPS Shareholders, persons with information rights and participants in the RPS Share Plans may request a hard copy of this announcement by: (i) telephoning Equiniti on +44 (0)345 504 9911 (lines will be open from 8.30 a.m. to 5.30 p.m., Monday to Friday (excluding public holidays in England and Wales)); or (ii) submitting a request in writing to Equiniti Limited, Aspect House, Spencer Road, Lancing, West Sussex BN99 6DA, United Kingdom. A person so entitled may also request that all future documents, announcements and information in relation to the Acquisition be sent to them in hard copy form.

If you are in any doubt about the contents of this announcement or the action you should take, you are recommended to seek your own independent financial advice immediately from your stockbroker, bank manager, solicitor or independent financial adviser duly authorised under the Financial Services and Markets Act 2000 (as amended) if you are resident in the United Kingdom or, if not, from another appropriate authorised independent financial adviser.

Certain figures included in this announcement have been subjected to rounding adjustments. Accordingly, figures shown for the same category presented in different tables may vary slightly and figures shown as totals in certain tables may not be an arithmetic aggregation of the figures that precede them.

Rule 2.9 Disclosure

In accordance with Rule 2.9 of the Code, RPS confirms that, as at 22 September 2022 (being the latest practicable date prior to the Rule 2.7 Announcement), it has in issue and admitted to trading on the main market of the London Stock Exchange 277,510,925 ordinary shares of three pence each. There are no ordinary shares held in treasury. The International Securities Identification Number (ISIN) of the ordinary shares is GB0007594764.

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