Theresa May’s top environmental adviser is backing new curbs on firearm licences, pheasant shooting and grouse moor management in what pro-blood sports MPs fear is a new “war” on field sports.

Sir John Randall, who works in the Number 10 policy unit, purportedly made the claims to campaigners in a private meeting and then told them that he had raised the activists' concerns personally with Michael Gove, the Environment secretary.

Sir John was a Government whip from 2010 to 2013. He was MP for Uxbridge from 1997 to 2010, and then MP for Uxbridge and South Ruislip from 2010 to 2015 when he was succeeded by Boris Johnson.

Sir John was appointed Mrs May’s environment adviser in 10 Downing Street last August after he quit as a Conservative MP in 2015. He is paid £72,000 a year to work part-time and is a former RSPB trustee.

He met with Findlay Wilde, a conservationist, and two other campaigners – Josie Hewitt, a wildlife photographer and Georgia Locock who has marched in protest against grouse shooting - in 10 Downing Street on November 23.

He then made the remarks in an emailed response to Mr Wilde's notes from the meeting, which was posted by the activist on his blog on December 4.