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

Premier Oil Plc

GB00B43G0577

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): Issue of shares in relation to acquisition of EnCore Oil plc

X

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

Ameriprise Financial, Inc. and its group

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

See additional information under 13.

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

17th January 2012

6. Date on which issuer notified:

19th January 2012

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

Below the threshold of 5%

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

GB00B43G0577

4,028,672

4,028,672

569,478

569,478

24,096,188

0.108%

4.555%

US7405361079

0

0

0

0

680

0.000%

0.000%

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

N/A

N/A

N/A

N/A

N/A

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

N/A

N/A

N/A

N/A

N/A

Nominal

Delta

N/A

N/A

Total (A+B+C)

Number of voting rights

Percentage of voting rights

24,666,346

4.663%

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

Ameriprise Financial, Inc., which through intermediate holding companies controls the voting rights of Columbia Management Investment Advisers, Columbia Wanger Asset Management, Threadneedle Management Luxembourg S.A. and Threadneedle Asset Management Holdings Ltd, which itself controls the voting rights of Threadneedle Asset Management Ltd, Threadneedle International Ltd and Threadneedle Pensions Ltd.

Proxy Voting:

10. Name of the proxy holder:

N/A

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

N/A

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

N/A

13. Additional information:

Registered Owner

Columbia Management Investment Advisers A/c 680

Littledown Nominees Ltd A/c ZLA08 37,132

Ameriprise Financial Inc A/c 252,357

Columbia Wanger Asset Management A/c 3,131,005

Chase Nominees Ltd A/c 75102 155,000

HSBC Global Custody Nominee (UK) Limited A/c 847452 406,563

HSBC Global Custody Nominee (UK) Limited A/c 740190 365,961

HSBC Global Custody Nominee (UK) Limited A/c 739874 1,303,617

HSBC Global Custody Nominee (UK) Limited A/c 740311 169,856

The Bank of New York (Nominees) Limited A/c PTG 15303/

09997799 30,776

Littledown Nominees Ltd A/c ZLA03 7,787,761

Littledown Nominees Ltd A/c 07198 486,189

Littledown Nominees Ltd A/c 27642 83,289

Littledown Nominees Ltd A/c 10478 13,657

Littledown Nominees Ltd A/c ZLA09 22,592

Littledown Nominees Ltd A/c 10479 10,874

Littledown Nominees Ltd A/c ZLA12 442,229

Littledown Nominees Ltd A/c ZLA14 117,770

Littledown Nominees Ltd A/c 07207 971,270

Littledown Nominees Ltd A/c 07196 45,701

Littledown Nominees Ltd A/c 07199 30,211

Mellon Nominees (UK) Ltd A/c WWSF0004002 336,098

Littledown Nominees Ltd A/c 10491 2,756,700

Littledown Nominees Ltd A/c 10488 2,169,472

Littledown Nominees Ltd A/c 10489 1,408,598

Littledown Nominees Ltd A/c 30337 47,000

Littledown Nominees Ltd A/c 31348 786,486

Littledown Nominees Ltd A/c ZLA15 1,297,772

14. Contact name:

Heather Kawan

Deputy Company Secretary

15. Contact telephone number:

02077301111