Ahead of the Conservative party's spring conference, David Cameron is increasingly worried about Tory backbench dissent - and about how much worse it could get after the AV referendum.

Please wait while this video loads. If it doesn't load after a few seconds you may need to have Adobe Flash installed.

David Cameron has been dropping in on his MPs in the Commons tearooms, asking them round to his place for drinks. Word has reached him that Tory MPs are not a happy bunch.

David Cameron doesn't have the authority of a party leader who swept his party to outright victory – and some of his MPs aren't quite sure what political journey they’re on.

You find plenty of Tory MPs complaining that the coalition with the Liberal Democrats has left them feeling that they’re out in the cold.

Many Conservative MPs say they feel marginalised by the coalition. They argue that David Cameron, with so many Lib Dem MPs' votes in his pocket, feels he doesn’t have to consult them.

David Cameron's been trying to address that with what's been called a "Twiglets and Chardonnay charm offensive". But it's not got the job done.

Many backbench Tories were furious a minister had briefed that an electoral pact with the Lib Dems might be a good idea.

The other big gripe you hear from Conservative MPs is that they feel they're not hearing enough about traditional Conservative policy areas: crime, defence, Europe, the family.

Many Tory backbenchers were uncomfortable with David Cameron's half-hearted campaign in the Oldham East by-election, effectively lending some Tory support to the Lib Dems there.

And they were furious when a Cabinet minister briefly anonymously that an electoral pact with the Lib Dems at the next general election might be a good idea.

Cameron's 'Twiglets and Chardonnay' offensive
"If he was a chocolate he’d eat himself." (Tory MP on David Cameron).

I've been talking to Tory backbench MPs, and I came across quite a bit of unhappiness with the general smoothness of David Cameron. There was resentment of his domestic arrangements (seeing more of his family, some MPs felt, than they do of their own… knocking off earlier, they felt, than some of them do). There’s an “It’s alright for him” mood abroad.

Anyway, that wasn’t the point of the exercise, though I did find it quite striking. The point was to see how rocky the mood was politically. On camera, Patrick Mercer calls it "fragile". He would say that, you might say. But he spoke on camera for many who would only speak privately. One senior backbencher said (off camera) that the mood was "febrile" and he "didn't know where it would go".

Read more of Gary Gibbon's blog: Cameron needds to order more wine and crisps

Talking to Tory MPs, you quickly pick up a sense of a generational difference as well. Many of the new MPs who came in in 2010 fought their seats unsuccessfully a few times beforehand. Many of them are sitting on fairly small majorities.

They tend to look down warily to their seat more than their predecessors, look up to the whips and the wielders of patronage a bit less. Many of them have already spoken out or rebelled more than previous generations of Tory MPs – and this government is not even one year old.

But right now the biggest worry on every Tory MPs lips is the alternative vote referendum in May. They worry that Nick Clegg will get his way: a change in the voting system, a change that one senior Tory MP told me would be like a dagger to the heart of the Conservative party. "It would never hold power outright again," he said.

It is not hard what that sort of result would do to the standing of David Cameron with his backbenchers.