Labour MPs in leave-voting areas who say they seldom meet voters who are having second thoughts on Brexit are failing to take account of the views of a “private majority” who have changed their mind, the People’s Vote campaign has claimed.

The group claimed the findings of a study showed many voters were staying under the radar of local party activists and social media analysts because they restricted their conversations on Brexit to friends, family and work colleagues.

The pressure group, which is pushing for a second referendum, said that while the analysis did not show that a fresh vote would result in the UK staying in the EU, it did suggest the picture on the doorstep did not reflect numbers changing their mind.

Peter Kellner, a pollster and former president of YouGov, said: “What it does show is that the people that politicians and activists speak to in their local communities could well provide a misleading guide to the public mood. The voice of the private majority is not loud, but it needs to be heard for it is likely to prove decisive.”

A YouGov poll of 3,300 people, commissioned by People’s Vote, found that among the 8% of voters who had had any contact with their MP, six out of every 100 had changed their mind on Brexit. Among those who engaged with some other forum such as a public meeting, radio phone-in or social media, 11 out of 100 were shifting.

In contrast, among the so-called “private majority” – who are believed to include around four out of every five voters – who had not had any of those public-facing interactions, 21 out of every 100 were having second thoughts on their original vote.

Kellner claimed the results suggested that MPs in leave-voting seats had – as both the Tories did in 2015 and Labour did in 2017 – failed to take account of the mood of the “private majority” in their local campaigning.

He said: “The voters who have contact with their MP are mainly men, mostly over 50 and usually have fixed political views. However, the voters who decide closely fought elections and referendums are, by their nature, those whose loyalties tend to shift.

“The people whose minds are changing – typically younger voters, especially women – belong to the private majority who are usually happy to discuss Brexit with friends, family and work colleagues, but otherwise keep their thoughts and doubts to themselves.”

People’s Vote has published the analysis in the hope of persuading those Labour MPs who have dismissed their previous polling that showed a majority of voters in all seats held by Labour support a second referendum. The support of Labour’s 257 MPs will be critical if a motion backing a second referendum is to pass the House of Commons.