A Conservative MP who broke lobbying rules in a WhatsApp exchange revealed by The Telegraph’s Lockdown Files investigation has said he will stand down at the next election.

Steve Brine, who has represented Winchester and Chandler’s Ford since 2010, said it was time for him to consider a “new chapter” in his life.

Mr Brine, the chairman of the Commons health and social care select committee, said in a letter to his local Tory association he had always intended to “serve for twenty years, or four general elections”.

“This wasn’t a hard and fast rule, and I don’t think anyone could have predicted the events of the past thirteen years, but it feels like the right time now, for both myself and the family,” he said.

“Going forward, I feel I can pursue some of the issues I care about - in health and perhaps elsewhere - outside Parliament as well as within.”

In March, a leaked WhatsApp message published as part of the Lockdown Files showed Mr Brine contacted ministers and officials on behalf of Remedium, which was paying him £1,600 a month.

Following an investigation, the watchdog concluded that Steve Brine twice failed to make clear he was a paid adviser to Remedium Partners when contacting ministers on behalf of the healthcare recruitment firm.

However, critics said that Mr Brine “got off lightly”, as he will face no further action beyond “rectifying” his breach with an apology and a promise not to do it again.

Winchester and Chandler’s Ford will be one of the key target seats for the Liberal Democrats at the next general election, widely expected next year.

At the 2019 general election, Mr Brine’s majority was 985, down from 9,999 two years before.

A Liberal Democrat source noted he was the latest in a string of Conservative MPs in ultra-marginal seats who have announced they will stand down before the next ballot.