Holding(s) in Company

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

Costain Group 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 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): Issuance of New Shares by the Company resulting in a dilution of voting rights

X

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

Mohammed Abdulmohsin Al-Kharafi & Sons Co. W.L.L.

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

BBHISL Nominees Limited (designation 125688)

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

March 18, 2014

6. Date on which issuer notified:

March 18 2014

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

13.76%

8. Notified details:

A: Voting rights attached to shares

Class/type of shares

 if possible using the ISIN CODE

Situation previous to the Triggering transaction

Resulting situation after the triggering transaction

Number of Voting Rights viii

Number of shares

Number of voting rights ix

% of voting rights

Direct x

Indirect xi

Direct

Indirect

ORD 50p SHARES

GB00B64NSP76

13,789,490

13,789,490

13,789,490

13,789,490

13.76%

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

-

Total (A+B)

Number of voting rights

% of voting rights

13,789,490

13.76%

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

Proxy Voting:

10. Name of the proxy holder:

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

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

13. Additional information:

14. Contact name:

Ahmed Samy

15. Contact telephone number:

+(965)-2483 0025

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

Full name (including legal form for legal entities)

 Mohammed Abdulmohsin Al-Kharafi & Sons WLL

Contact address (registered office for legal entities)

P.O.Box 886 - Safat 13009 - Kuwait

Phone number

+(965)-2483 0025

Other useful information (at least legal representative for legal persons)

Attention:- Ahmed Samy

B: Identity of the notifier, if applicable XVii

Full name

Ahmed Samy

Contact address

P.O.Box 886 - Safat 13009 - Kuwait

Phone number

+(965)-2483 0025

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

DDG Investment Affairs - Mohammed Abdulmohsin Al-Kharafi & Sons WLL

C: Additional information