Costain Regulatory News (COST)

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARES

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

Yes

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):

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

Legal & General Group Plc (L&G)

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

N/A

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

18 March 2010

6. Date on which issuer notified:

19 March 2010

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

L&G (From 4% to 3%)

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 Shares

Number of Voting Rights

Number of shares

Number of voting rights

% of voting rights

Direct

Indirect

Direct

Indirect

ORD 5P

 25,858,465

(as on 22/09/2009)

 25,263,070

 25,263,070

3.98%

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financial instrument

Expiration date

Exercise/ Conversion Period

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

Expiration date

Exercise/ Conversion period

Number of voting rights instrument refers to

% of voting rights

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

 25,263,070

3.98%

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 the proxy holder:

N/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

13. Additional information:

Notification using the total voting rights figure of  634,248,713

14. Contact name:

Joanne Shelton (LGIM)

15. Contact telephone number:

020 3124 3850