Senior MoD figures thought Gavin Williamson caused national security leak

Exclusive: former government insider said it was believed serious breach could have only come from Gavin'

Penny Mordaunt was forced to deal with a security leak during her time as defence secretary that the department believed came from her predecessor, Gavin Williamson, amid fears the information put our people's lives at risk".

Three sources told the Guardian that the breach was deemed so serious that Mordaunt was prepared to seek a D notice to warn any media considering publishing the information that it risked endangering Britain's national security.