Costain Group PLC
("Costain" or "the Company")

Transactions in shares by Persons Discharging Managerial Responsibilities ("PDMRs")

This notification is made in accordance with DTR 3.1.4R (1) (a).

(a)  Total Beneficial Holding of Shares

Costain announces that, following the exercise of share awards granted under the Company's Long Term Incentive Plan as detailed in section (b) below, the following Director held the number of ordinary shares of 50 pence each in the share capital of the Company (the 'Shares') as set out in the table below:

(b)   Long Term Incentive Plan

On 07 May 2013, awards were granted under the Costain Group PLC Long Term Incentive Plan (the "Plan") to certain Directors of the Company. The awards were granted in the form of options with a nil exercise price over a fixed number of Shares (the "Award"). No consideration was paid for the grant of the Award. The Award became exercisable on 07 May 2016 for a period of up to ten years from the date of grant.

On 16 May 2016, the Company was advised that ACS HR Solutions Share Plan Services (Guernsey) Limited, as Trustee of the Costain Group Employee Trust, had undertaken the following transactions:

On 13 May 2016, the following Director exercised his options to acquire the number of Shares as set out in the table below. As detailed below, the director concerned sold a proportion of the resulting Shares, in order to satisfy his income tax and national insurance liability arising on exercise, and retained the remaining Shares.

* as adjusted following the Capital Raising in March 2014

 16 May 2016

Enquiries:

Costain Group PLC                                                                                            Tel: 01628 842444
Tracey Wood

Company Secretary