Following the news, Prospect deputy general secretary Garry Graham said:

“The expert staff at DSTL make a vital contribution to national security, and we are proud of all the Prospect members who have contributed to this, demonstrating the value of constructive working between unions and employers.

“However all of this is at risk as the pay cap means that pay at DSTL continues to lag behind their competitors in the private sector and other areas of the civil service, storing up long term problems in recruitment and retention.

“Urgent action is needed to rectify the situation to ensure DSTL can continue to retain the skilled staff whose expertise keeps this country safe.”