Holding(s) in Company

RNS Number : 4213K

Tullow Oil PLC

19 April 2010

TR-1(i): NOTIFICATION OF MAJOR INTERESTS IN SHARES

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

TULLOW OIL PLC

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

An acquisition or disposal of voting rights: ( X )

An acquisition or disposal of 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 ( X )

An event changing the breakdown of voting rights: ( )

Other (please specify): ( )

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

BlackRock, Inc.

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

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

15 April 2010

6. Date on which issuer notified:

16 April 2010

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

Holding has gone above 12%

8. Notified details:

A: Voting rights attached to shares ^{viii, ix}

Class/type of shares if possible using the ISIN CODE

Situation previous to the Triggering transaction

Ord 10p
GB0001500809

Number of shares

105,178,322

Number of Voting Rights

105,178,322

Resulting situation after the triggering transaction
Class/type of shares if possible using the ISIN CODE	Number of shares	Number of voting rights		% of voting rights
	Direct	Direct	Indirect	Direct	Indirect
Ord 10p GB0001500809	N/A	N/A	105,613,765	N/A	11.91%

B: Financial Instruments

Resulting situation after the triggering transaction (xii)

Type of financial instrument	Expiration Date (xiii)	Exercise/Conversion Period/ Date (xiv)	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	Exercise date ^xvii	Exercise / Conversion Period ^xviii	Number of voting rights instruments refers to	% of voting rights ^{xix, xx}
CFD				1,342,039	Nominal	Delta
					0.15%	0.15%