Public Opening Position Disclosure

(a) Identity of the party to the offer making the disclosure:

Premier Oil plc ("Premier")

(b) Owner or controller of interests and short positions disclosed, if different from 1(a):The naming of nominee or vehicle companies is insufficient

N/A

(c) Name of offeror/offeree in relation to whose relevant securities this form relates:Use a separate form for each party to the offer

EnCore Oil plc ("EnCore")

(d) Is the party to the offer making the disclosure the offeror or the offeree?

Offeror

(e) Date position held:

5 October 2011

(f) Has the party previously disclosed, or is it today disclosing, under the Code in respect of any other party to this offer?

No

Class of relevant security:

Ordinary Shares

Interests

Short positions

Number

%

Number

%

(1) Relevant securities owned and/or controlled:

Nil

-

Nil

-

(2) Derivatives (other than options):

Nil

-

Nil

-

(3) Options and agreements to purchase/sell:

Nil

-

Nil

-

TOTAL:

Nil

-

Nil

-

Class of relevant security in relation to which subscription right exists:

None

Details, including nature of the rights concerned and relevant percentages:

None

Details of any irrevocable commitments or letters of intent procured by the party to the offer making the disclosure or any person acting in concert with it (see Note 3 on Rule 2.11 of the Code):

Premier has received irrevocable undertakings from the directors of EnCore to vote, or to procure that the registered holder votes, in favour of the resolutions relating to the acquisition of the entire issued ordinary share capital of Encore by Premier (the "Acquisition") to be implemented by way of a court sanctioned scheme of arrangement (the "Scheme") under Part 26 of the Companies Act 2006 (or, in the event that the Acquisition is implemented by means of a takeover offer (as such term is defined in section 974 of that Act) (the "Offer"), to accept or procure acceptance of the Offer) in respect of 21,692,984 Encore ordinary shares, representing approximately 7.41% of the current issued share capital of EnCore.

Name

Total number ofexisting EnCore shares

Percentage of EnCoreissued share capital(excluding shares under option)

Alan Booth

6,650,000

2.27%

Eugene Whyms

5,900,000

2.02%

Graham Doré

4,550,000

1.55%

James Clark

2,110,327

0.72%

Christine Wheeler

2,250,657

0.77%

Vivien Gibney

232,000

0.08%

Total

21,692,984

7.41%

The executive directors of EnCore (the "Executive Directors") have also irrevocably undertaken to elect for new Premier shares instead of all or part of the cash consideration they would otherwise be entitled to receive under the Acquisition (the "Share Alternative"). The undertakings to acquire the Share Alternative apply in respect of 32,543,859 Encore ordinary shares, representing their total number of existing EnCore shares and the EnCore shares to be issued to them under options.

Name

Total number ofexisting EnCore shares

Total number of shares under options

Total number of EnCore shares plus shares under options

Alan Booth

6,650,000

3,895,883

10,545,883

Eugene Whyms

5,900,000

3,895,883

9,795,883

Graham Doré

4,550,000

3,345,883

7,895,883

James Clark

2,110,327

2,195,883

4,306,210

Total

19,210,327

13,333,532

32,543,859

These irrevocable undertakings cease to be binding if: (i) the Scheme document has been issued and the Scheme has not become effective by 5.00 p.m. on 28 February 2012 and prior to that time (should the Acquisition be implemented by way of takeover offer) Premier has not issued an Offer document; or (ii) an Offer document is issued before 5.00 p.m. on 28 February 2012 and the Offer lapses or is withdrawn without having become wholly unconditional. 

The obligations under these irrevocable undertakings extend to any shares arising or to arise pursuant to the exercise of options held by the Executive Directors. However, the Executive Directors shall not be obliged to elect for the Share Alternative in relation to shares arising or to arise under any options until the date on which the court sanctions the Scheme or the Offer becomes unconditional in all respects (as the case may be) or such later date as Premier and Encore may otherwise agree.

Premier has also received a letter of intent from BlackRock Investment Management (UK) ("BlackRock") acting as investment manager on behalf of clients who are the beneficial holders of, or have other interests, in shares in EnCore confirming that it is BlackRock's current intention to vote in favour of the resolutions relating to the Acquisition pursuant to the Scheme (or, in the event that the Acquisition is implemented by means of the Offer), to accept or procure acceptance in respect of the Offer in respect of the shares in EnCore which BlackRock is able to control.

The letter of intent from BlackRock is not legally binding and BlackRock (subject to applicable law) retains the right to deal with the EnCore shares that it controls in its absolute discretion and/or on the instructions of its clients.

As at close of business on 3 October 2011, BlackRock was interested in 17,049,983 EnCore shares (representing approximately 5.83% of the current issued share capital of EnCore) and had the ability to control the voting rights attached to all such shares.

Details of any interests, short positions and rights to subscribe of any person acting in concert with the party to the offer making the disclosure:

None.

It has not been practicable for Premier to make enquiries of all of its concert parties in advance of releasing this Opening Position Disclosure and therefore this Opening Position Disclosure does not include all relevant details in respect of Premier's concert parties.

Premier confirms that a further disclosure in accordance with Rule 8.1(a) and Note 2(a)(i) on Rule 8 of the Code will be made as soon as possible, if required.

Details of any indemnity or option arrangement, or any agreement or understanding, formal or informal, relating to relevant securities which may be an inducement to deal or refrain from dealing entered into by the party to the offer making the disclosure or any person acting in concert with it:

If there are no such agreements, arrangements or understandings, state "none"

None

Details of any agreement, arrangement or understanding, formal or informal, between the party to the offer making the disclosure, or any person acting in concert with it, and any other person relating to:

(i) the voting rights of any relevant securities under any option; or

(ii) the voting rights or future acquisition or disposal of any relevant securities to which any derivative is referenced:

If there are no such agreements, arrangements or understandings, state "none"

None

Supplemental Form 8 (Open Position)

No

Supplemental Form 8 (SBL)

No

Date of disclosure:

5 October 2011

Contact name:

Andy Gibb

Telephone number:

+44 (0)20 7730 1111