There is a delicious irony in the fact that David Cameron, who ended up promising his party a referendum so as to avoid Europe tearing apart his government just as it tore apart John Major’s back in the 1990s, has ended up parroting his predecessor’s much-mocked mantra: ‘negotiate and decide.’

That said, it looks as though the Prime Minister – unlike his predecessor – has actually persuaded most his parliamentary colleagues, and most of his grassroots, that this line makes sense, at least for now. With the help of the ESRC’s UK in a Changing Europeinitiative, directed by Anand Menon, we commissionedIpsosMori to ask just under a hundred MPs for their views on EU issues. Six out of ten Conservative MPs said that their vote in the referendum would depend on the result of the PM’s negotiations.

Moreover just over half of Tory MPs say they expect those negotiations to make at least ‘a fair amount’ of difference to our relationship with the EU. That said, that still leaves nearly four out of ten saying they don’t think the negotiations will achieve much, albeit only one in ten who think they will make no difference at all.

It’s also very noticeable that those who say their vote will depend on the outcome of Cameron’s efforts are more likely to expect them make a difference. That might mean that that they are primed to believe that he is going to get something good enough to allow them ultimately to plump for Remain rather than Leave.

What’s striking, too, is that Conservative MPs’ views on the basic question of how they’re planning to vote in the referendum are very much in line with those of grassroots party members.  Just after the general election, a survey conducted for an ongoing, ESRC-funded study of party membership in the UK run by Queen Mary University of London and Sussex University asked those members the same question on the referendum as we’ve just asked MPs. Some 11 per cent of Tory MPs say that they ‘will vote for the UK to remain a member of the EU regardless of any re-negotiated terms of membership’ – the answer ticked by 19 per cent of grassroots members.

On the other side of the fence, some 20 per cent of Conservatives in the Commons say that they ‘will vote for the UK to leave the EU regardless of any renegotiated terms of membership’ – a hard-core Eurosceptic response echoed by 15 per cent of Conservative members out in the country.

But by far the most common response among both MPs and grassroots members is support for ‘negotiate and decide’.  Some 61 per cent of the former and 63 per cent of the latter say their vote would ‘depend on the terms of any renegotiations of our membership of the EU.’

The Prime Minister, then, appears to have convinced Tories from top to bottom not to rush to judgement – an achievement in itself, given quite how Eurosceptic it has become over the years.

Of course, because we’re taking about surveys, there’s an inevitable margin of error.  When it comes to members this is pretty small: +/- 3 per cent. When it comes to our MPs, it’s more significant – and therefore worth dealing with head-on rather than waiting for those determined to hole us ‘below the line’ to do their damndest.

Worst case, as it were, the number of Conservative MPs wanting to leave come-what-may could be as high as a hundred but it could also be under 40.  Likewise, the number ‘waiting and seeing’ could run to as many as 250 or as few as 150.  Still, better a range based on research than a finger in the wind or even a reliance on voting behaviour in parliament – much as we believe, of course, in the validity of the latter!  In any case, the results we’ve obtained seem reassuringly clear-cut.

That’s certainly the case when it comes to how Tory MPs think the country will vote in the upcoming referendum.  True, there is a tendency for those definitely wanting out to bet the public will end up going their way, while those who have already made up their mind to vote to stay think voters will ultimately veer in their direction. But two thirds of Conservative MPs reckon Remain will win the day, and only a third believe that Britain will vote for Brexit.

This could well prove crucial: Tory MPs are only human; if their money, smart or otherwise, is on the UK remaining a member state, then they may well decide (especially if they believe that promotion is more likely to come to those who toe the line rather than rock the boat) to take the path of least resistance.  In which case the Prime Minister, and not the better-off-outers, will have the momentum and the majority of the parliamentary party on his side – something that may well carry weight with voters, many of whom are still to make up their minds.

We can also say with some confidence that Cameron is absolutely right to try to get something out of Brussels on migrant benefits in particular and on red tape more generally.  Both are seen to be crucial issues by the overwhelming majority of Conservative MPs, three quarters of whom agree with the proposal that people should only be able to claim welfare in their country of origin, with the same proportion saying that when they think of the EU they think ‘bureaucracy’.

He is also right, we think, to recognise that the dominant emotion aroused by the EU among Tory MPs is ‘unease’ rather than ‘anger’, with only a quarter saying it makes them feel the latter, compared to just over two-thirds who pick the former.

If the Prime Minister Cameron can get a package which speaks to this unease, even if it doesn’t definitively deal with it, then our research suggests (to borrow from Mr Major once again) that most of his colleagues will ‘shut up’ rather than ‘put up’ – at least, that is, until after he wins his referendum.