Holding(s) in Company

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARESi

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

Altona Energy 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):

In-Specie Transfer out

X

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

Invesco Limited

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

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

19 April 2011

6. Date on which issuer notified:

20 April 2011

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

17%, 16%

8. Notified details:

A: Voting rights attached to shares viii, ix

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 x

Direct

Direct xi

Indirect xii

Direct

Indirect

Ordinary 1p Shares

74,188,660

74,188,660

71,358,876

16.93%

GB00B06GJT32

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financialinstrument

Expirationdate xiii

Exercise/Conversion Period xiv

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

% of votingrights

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments xv, xvi

Resulting situation after the triggering transaction

Type of financialinstrument

Exercise price

Expiration date xvii

Exercise/Conversion period xviii

Number of voting rights instrument refers to

% of voting rights xix, xx

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

71,358,876

16.93%

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

Bank of Ireland (Dublin) - 12,029,532

Bank of New York - 26,072,315

Bank of New York Mellon - 141,523

HSBC Bank plc, London - 11,926,129

State Street Trust & Banking Co, London - 21,032,496

Trust & Custody Services JP - 156,881

Proxy Voting:

10. Name of the proxy holder:

11. Number of voting rights proxy holder will ceaseto hold:

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

13. Additional information:

14. Contact name:

Sam Edwards

15. Contact telephone number:

01491 416381

Note: Annex should only be submitted to the FSA not the issuer

Annex: Notification of major interests in share

A: Identity of the persons or legal entity subject to the notification obligation

Full name

(including legal form of legal entities)

Contact address

(registered office for legal entities)

Phone number & email

Other useful information

(at least legal representative for legal persons)

B: Identity of the notifier, if applicable

Full name

Invesco Limited

Contact address

Registered address:

30 Finsbury Square

London

EC2A 1AG

Phone number & email

020 7638 0731

Other useful information

(e.g. functional relationship with the person or legal entity subject to the notification obligation)

C: Additional information

For notes on how to complete form TR-1 please see the FSA website.