Completion of Gartmore acquisition

Completion of Gartmore acquisition

4 April 2011

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

On Friday 1 April 2011, Henderson Group announced that the Grand Court of the Cayman Islands had sanctioned the proposed scheme of arrangement under section 86 of the Cayman Companies Law (the "Scheme"), pursuant to which Henderson Group plc ("Henderson Group") would acquire the entire issued share capital of Gartmore Group Limited ("Gartmore") (the "Acquisition"). Henderson Group is pleased to confirm that the Scheme became effective, and the Acquisition completed, at 8:00 a.m. (London time) this morning.

Commenting on the Acquisition, Andrew Formica, Chief Executive of Henderson Group, said: "I am pleased with the strong support we received from shareholders on our acquisition of Gartmore. Our attention now moves to bringing across fund managers and staff and integrating the business onto our own platform. The combination of the two groups improves our offering to clients by expanding our product range and makes us one of the largest UK retail fund managers and a key player in the absolute return market. I am confident that together we will create significant value for clients and shareholders."

The 242,639,403 New Henderson Group Shares issued to Scheme Shareholders were admitted to the Official List with a premium listing, and to trading on the London Stock Exchange's main market for listed securities at 8:00 a.m. London time today.

Terms defined in the prospectus issued by Henderson Group in connection with the

Acquisition (the "Prospectus") have the same meaning in this announcement.

Update on Gartmore fund flows

As announced on 12 January 2011, Gartmore AUM as at 31 December 2010 was £16.5bn (including notified redemptions). Since 31 December 2010, and up to and including 30 March 2011, Gartmore has experienced £1.2bn of net outflows (including notified redemptions as at that date). In addition, given overall market volatility, market levels have had a negative impact on AUM.

Henderson Group plc47 EsplanadeSt HelierJersey JE1 0BDRegistered in JerseyNo. 101484ABN 67 133 992 766

UBS Limited (lead financial adviser, sponsor and corporate broker to Henderson Group)John Humphrey Tel: +44 (0)20 7567 8000James RobertsonRahul Luthra

Ondra LLP (trading as Ondra Partners) (joint financial adviser to Henderson Group)Michael Tory Tel: +44 (0)20 7082 8750Stewart BennettElena Ciallie

UBS Limited is acting exclusively as lead financial adviser, sole corporate broker and sponsor to Henderson Group and no-one else in relation to the Proposed Acquisition and will not be responsible to anyone other than Henderson Group for providing the protections offered to clients of UBS Limited nor for providing advice in relation to the matters described in this announcement or in relation to the Proposed Acquisition.

Ondra Partners, authorised and regulated in the UK by the FSA, is acting exclusively as joint financial adviser to Henderson Group and no-one else in relation to the Proposed Acquisition and will not be responsible to anyone other than Henderson Group for providing the protections offered to clients of Ondra Partners nor for providing advice in relation to the matters described in this announcement or in relation to the Proposed Acquisition.

Other than their responsibilities to Henderson Group, UBS Limited and Ondra Partners do not accept any responsibility whatsoever for the contents of this announcement or for any statement made or purported to be made by either of them or on their behalf in connection with the Proposed Acquisition. Each of UBS Limited and Ondra Partners accordingly disclaims all and any other liability whether arising in tort, contract or otherwise which either of them might otherwise have in respect of this announcement or any such statement.

The release, publication or distribution of this announcement in jurisdictions other than the United Kingdom and Australia may be restricted by law and, therefore, any persons who are subject to the laws of any jurisdiction other than the United Kingdom or Australia should inform themselves about, and observe, any applicable requirements. Failure to comply with any such restrictions may constitute a violation of the securities laws of any such jurisdiction. This announcement has been prepared to comply with the requirements of English and Australian law, the Listing Rules, the rules of the LSE and the ASX Listing Rules and 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 or Australia.

This announcement is for information purposes only and does not constitute, or form part of, any offer for or invitation to sell or purchase any securities, or any solicitation of any offer for, securities in any jurisdiction. This announcement does not constitute a prospectus or a prospectus equivalent document.

The New Henderson Group Shares have not been, and will not be, registered under the Securities Act or under the securities laws of any state, district or other jurisdiction of the United States or of any Restricted Jurisdiction and no regulatory clearances in respect of the registration of New Henderson Group Shares have been, or will be, applied for in any such jurisdiction. The New Henderson Group Shares have been issued in reliance upon the exemption from the registration requirements of the Securities Act provided by section 3(a)(10) thereof. The Acquisition has not been, and will not be, approved or disapproved by the SEC, nor has the SEC or any US state securities commission passed upon the merits or fairness of the transaction nor upon the adequacy or accuracy of the information contained in the Prospectus. Any representation to the contrary is a criminal offence in the United States. Under applicable US securities laws, Gartmore Shareholders who were or will be 'affiliates' of Henderson Group prior to or after the Effective Date will be subject to certain transfer restrictions relating to the New Henderson Group Shares received in connection with the Scheme.

The contents of Henderson Group's website or of any website accessible via hyperlinks from Henderson Group's website are not incorporated into, and do not form part of, this announcement.