Notification of Interest

1. Identity of the issuer or the underlying issuer of existing shares to which voting rights are attached:

Hydrodec Group plc

2 Reason for the notification (please tick the appropriate box or boxes):

An acquisition or disposal of voting rights

√

An acquisition or disposal of qualifying financial instruments which may result in the acquisition of shares already issued to which voting rights are attached

An acquisition or disposal of instruments with similar economic effect to qualifying financial instruments

An event changing the breakdown of voting rights

Other (please specify):

CHANGE TO THE NUMBER OF VOTING RIGHTS IN ISSUE, FOLLOWING THE RECENT FIRM PLACING.

√

3. Full name of person(s) subject to the notification obligation:

Aviva plc & its subsidiaries

4. Full name of shareholder(s)  (if different from 3.):

Registered Holder:

BNY Norwich Union Nominees Limited  6,795,212*

Chase (GA Group) Nominees Limited 42,755,594*

CUIM Nominee Limited 4,387,169*

*denotes direct interest

BNP Paribas - London  2,320,901

Chase Nominees Limited 8,047,711

State Street Nominees Limited 6,592,193

5. Date of the transaction and date on which the threshold is crossed or reached:

01 October 2010

6. Date on which issuer notified:

04 October 2010

7. Threshold(s) that is/are crossed or reached:

19% to 20% Change at Combined Interest Level

8. Notified details:

A: Voting rights attached to shares

Class/type of shares

if possible using the ISIN CODE

Situation previous to the triggering transaction

Resulting situation after the triggering transaction

Number of Shares

Number of Voting Rights

Number of shares

Number of voting rights

% of voting rights

Direct

Direct

Indirect

Direct

Indirect

Ordinary Shares GB00B02FJF09

60,898,780

60,898,780

70,898,780

53,937,975

16,960,805

15.80%

4.97%

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financial instrument

Expiration date

Exercise/ Conversion Period

Number of voting rights that may be acquired if the instrument is exercised/ converted.

% of voting rights

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financial instrument

Exercise price

Expiration date

Exercise/ Conversion period

Number of voting rights instrument refers to

% of voting rights

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

70,898,780

20.77%

9. Chain of controlled undertakings through which the voting rights and/or the financial instruments are effectively held, if applicable:

The voting rights are managed and controlled by Aviva Investors Global Services Limited, with the following chain of controlled undertakings:-

Aviva Investors Global Services Limited:

·; Aviva plc (Parent Company)

·; Aviva Group Holdings Limited (wholly owned subsidiary of Aviva plc)

·; Aviva Investors Holdings Limited (wholly owned subsidiary of Aviva Group Holdings Limited)

·; Aviva Investors Global Services Limited (wholly owned subsidiary of Aviva Investors Holdings Limited)

Proxy Voting:

10. Name of the proxy holder:

See Section 4

11. Number of voting rights proxy holder will cease to hold:

12. Date on which proxy holder will cease to hold voting rights:

13. Additional information:

Figures are based on a revised total number of voting rights of 341,381,198, following the recent firm placing of shares.

14. Contact name:

Neil Whittaker

15. Contact telephone number:

01603 684420