By Matthew Barrett and Tim Montgomerie

On Wednesday, we reported that Tory MPs at the 1922 Committee wanted to "get those yellow b**tards", in reference to Liberal Democrats who were criticising Andrew Lansley's NHS reforms, having voted for it before.

In today's Mail on Sunday James Forsyth writes that 10 Downing Street is at the end of its tether in having to deal with the Liberal Democrats. They agree one thing one day and then revisit that agreement the next day. "It is like negotiating with an Italian," reports James, "You think everything has been agreed and shaken on, only for the other side to start demanding concessions before the deal goes ahead."

So, who are the real troublemakers on the Liberal Democrat side of the Coalition? Here's a rough guide...

Vince Cable: Cable's time in office, as the Secretary of State for Business, Innovation and Skills, has not been a happy one - for him or his Cabinet colleagues. He threatened to abstain on his own tuition fees policy, admitted he thought about resigning over his BSkyB gaffe, and also implied he might prefer life outside government. He called David Cameron's modest speech on immigration "very unwise" and, as Paul Goodman pointed out last week, business doesn't think much of him. As Charles Moore pointed out last week in a devastating column the tuition fees policy has become a terrible dog's breakfast: students oppose the debt, the Treasury isn't going to save much money and universities won't get the scale of resources they need to deliver world class courses. Well done Vince.

Chris Huhne: After numerous instances of criticising Conservatives over the AV referendum, Huhne is certainly one of the Premier League's Big Four. He has threatened to sue his Coalition partners and likened the first Muslim member of Britain's Cabinet to Goebbels. His climate change plan, although diluted by the Chancellor, threatens to wreck Britain's economic recovery, as Nigel Lawson warned yesterday. If he survives his formidable intellectual skills will mean his environmental policies could become a massive political problem for Cameron but his immediate future rests in the hands of the Essex police.

Simon Hughes: Hughes, the deputy leader of the Lib Dems, frustrated the Coalition on tuition fees - by not committing to voting for, or against the policy, then criticising the plans, then abstaining on the vote, then agreeing to be a "social mobility tsar", and then criticising the policy some more. Outside of tuition fees, Hughes led rebellions against the rise in VAT and housing benefit cuts, and said Baroness Warsi was "inventing facts" during the AV referendum. Most recently, Hughes has opposed the NHS bill (that he voted for), and said it needed "fundamental" change for him to vote for it again.

Lord Oakeshott: He's not the highest profile Yellow B**tard but certainly, behind-the-scenes, one of the most dangerous. Personally close to Cable and tactically close to Huhne, Oakeshott attacked George Osborne as "incompetent" when he resigned as a Lib Dem Treasury spokesman earlier this year. "He hates Tories," said one ConHome source and is stirring up opposition in the upper house to the Coalition's NHS and police commissioner plans.