THERESA May’s chief of staff made a humiliating gaffe by accidentally flagging up sleazy porn videos on Twitter.

The Prime Minister’s right-hand man Gavin Barwell “regretted the embarrassment” his after-hours slip-up caused, a No10 source said.

The married dad-of-three, ousted as an MP last year, inadvertently hit the “reply” button on a thread of X-rated films at 9.21pm on Monday.

The videos named the websites Illustrated Interracial, Blacked and Moms Lick Teens, featuring women dressed as schoolgirls.

Mr Barwell, 46, is the jointhighest-paid Special Advisor in government, earning £140,000 a year – almost as much as the PM.

He did not post the pornographic clips himself, but pressing “reply” brought them to the attention of some of his 22,000 followers.

His reply was blank apart from the Twitter handles of those he replied to, suggesting he hit “reply’” and “send” with no message.

The reply stayed online for about 36 hours but was deleted yesterday after journalists highlighted it.