Notification of Interest

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARES

1. Identity of the issuer or the underlying issuerof existing shares to which voting rights areattached:

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):

On market transfer between direct and indirect funds

√

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

Aviva plc & its subsidiaries

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

Registered Holder:

BNY Norwich Union Nominees Limited 7,795,212*

Chase (GA Group) Nominees Limited 47,497,787*

CUIM Nominee Limited 4,477,169*

*denotes direct interest

BNP Paribas - London  2,370,901

Chase Nominees Limited 8,757,711

5. Date of the transaction and date onwhich the threshold is crossed orreached:

20 January 2011

6. Date on which issuer notified:

21 January 2011

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

15% to 16% Change at Direct Interest Level

8. Notified details:

A: Voting rights attached to shares

Class/type ofshares

if possible usingthe ISIN CODE

Situation previousto the triggeringtransaction

Resulting situation after the triggering transaction

NumberofShares

NumberofVotingRights

Numberof shares

Number of votingrights

% of voting rights

Direct

Direct

Indirect

Direct

Indirect

Ordinary SharesGB00B02FJF09

Direct:

53,937,975 (15.19%)

Indirect:

16,960,805 (4.77%)

Direct:

53,937,975 (15.19%)

Indirect:

16,960,805 (4.77%)

70,898,780

59,770,168

11,128,612

16.83%

3.13%

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financialinstrument

Expirationdate

Exercise/Conversion Period

Number of votingrights that may beacquired if theinstrument isexercised/ converted.

% of votingrights

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

Resulting situation after the triggering transaction

Type of financialinstrument

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

19.96%

9. Chain of controlled undertakings through which the voting rights and/or thefinancial 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 ceaseto hold:

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

13. Additional information:

Figures are based on a total number of voting rights of 355,181,198 as per the Company's Total Voting Rights Announcement of 29/10/2010.

14. Contact name:

Neil Whittaker, Aviva plc

15. Contact telephone number:

01603 684420