TR-1: Notifications of Major Interests in Shares

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

Offshore Hydrocarbon Mapping plc

2. Reason for notification (yes/no)

An acquisition or disposal of voting rights

Yes

An acquisition or disposal of financial instruments which may result in the acquisition of shares already issued to which voting rights are attached 

An event changing the breakdown of voting rights

Other (please specify):______________

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

Vontobel Asset Management

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

Vontobel European Mid and Small Cap

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

5 May 2009

6. Date on which issuer notified:

13 May 2009

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

3%

8: Notified Details

A: Voting rights attached to shares

Class/type of shares

If possible use ISIN code

Situation previous to the triggering transaction

Resulting situation after the triggering transaction

Number of shares

Number of voting rights

Number of shares

Number of voting rights

Percentage of voting rights

Direct

Indirect

Direct

Indirect

GB000003427219

1,300,000

1,300,000

zero

zero

zero

zero

zero

B: Financial Instruments

Resulting situation after the triggering transaction

Type of financial instrument

Expiration date

Exercise/ conversion period/date 

No. of voting rights that may be acquired (if the instrument exercised/converted)

Percentage of voting rights

Total (A+B)

Number of voting rights

Percentage of voting rights

Nil

n/a

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

Proxy Voting:

10. Name of proxy holder:

RBC Dexia Investor Services Bank S.A.

11. Number of voting rights proxy holder will cease to hold:

n/a

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

n/a

Offshore Hydrocarbon Mapping plc 

Bob Auckland - Finance Director

Telephone

0870 429 6581