What have the Lib Dems ever done for us? Actually, Mr Cameron’s ‘little black book’ outlines it all very nicely

It’s only a bit of Lib Dem fun, but it might just get serious at the election

The IPPR study suggests that Nick Clegg may have got his sums wrong (Getty Images)

What have the Romans ever done for us?” Tony Blair used to quote the great line from “Monty Python’s Life of Brian” when he replied sardonically to whingeing by trade unions that New Labour did nothing for them. He would then list the national minimum wage, the EU’s social chapter, the right to union recognition, paid holidays and so on.

In a more serious form, the Monty Python question is in the minds of Liberal Democrats, as their minds turn to the 2015 general election. They know that many voters will be asking what the Lib Dems have actually done for them in the past five years.

Nick Clegg believes he was given a helping hand in answering the question this week by an unexpected source – David Cameron. The Prime Minister told The Spectator magazine he is keeping a “little black book” of policies blocked by the Lib Dems, for use in the Conservatives’ manifesto in 2015. They include welfare reform, Europe, reducing business taxes and a further cut in the top rate of income tax from 45p to 40p.

When they read reports of the interview at their daily 8.45am meeting, Mr Clegg’s communications team could hardly believe their luck. They were in no doubt Mr Cameron was amplifying the main message in Mr Clegg’s speech to the Lib Dem conference in September, when he rattled off 15 hardline Tory policies his party had proudly halted in their tracks. When told about Mr Cameron’s little black book, a delighted Mr Clegg said: “We should be broadcasting this. The PM is coming out with one of our key messages. Tell people about it.”

So the Lib Dems have already written their own version of the “Little black book by David Cameron”. Voters will get the chance to read it at the election. Here are Mr Clegg’s favourite spoof “diary entries” by Mr Cameron:

5 September 2011: “Michael Gove and I had a brilliant idea the other day. Why not let private companies take over schools and run them for profit? But today Nick Clegg ruled that out!”

21 May 2012: “Bad news –another jobs plan scuppered. Adrian Beecroft [the venture capitalist and Tory donor] came up with an idea to let bosses fire workers at will. He says it will help create more jobs. But that pesky Vince Cable said he wouldn’t let it happen. Bring on a Tory majority!!”

25 April 2013: “Today Nick blocked my Snooper’s Charter, which was a great plan to keep records of everyone’s texts and emails. Civil liberties were great in opposition, but why on earth are the Lib Dems still protecting them now they’re in government?”

At one level, it’s only a bit of Lib Dem fun, but it might just get serious at the election. It’s also sign of more honest phase in the Coalition’s life in which the two parties acknowledge their differences publicly – healthy and inevitable as the election clock ticks.

Interestingly, Mr Cameron’s apparently off-the-cuff remark might not be the gaffe that the Lib Dems assume. Lynton Crosby, the Tories’ hard-nosed Australian election strategist, has been nagging him to spell out more clearly why he wants an overall majority in 2015 – and be more open about the shackles imposed by the Lib Dems now. The main aim is to woo back natural Tory voters who have drifted off. A secondary purpose is to reassure right-wing Tory MPs, many of whom suspect Mr Cameron would secretly prefer a second Lib-Con coalition to a narrow Tory majority that would allow his backbench critics to push him around.

They may be right about that. Yet some Tory modernisers who supported Mr Cameron’s “decontamination” strategy in opposition are worried that he is being lured rightwards after warnings that the Lib Dems are “recontaminating” the Tory brand. These mods point out that Mr Cameron will need to attract centre-ground voters in 2015 as well as win back the Tory core vote. Their anxieties surfaced last month when Nick Boles, the Planning Minister and an uber-moderniser, warned that young people saw the Tories as “alien” and said many voters would not even consider backing the party because of its unappealing image.

There was a time when Mr Cameron believed he failed to win an overall majority in 2010 because his Tory modernisation project had not been completed. Some mods wonder whether he still holds that view today. Cameron allies insist he is not veering right and that, when the election comes, he will chase the centre ground.

That message may jar with an ambition to reduce the top tax rate to 40p, which would be attacked by Labour and the Lib Dems as “another tax cut for millionaires”. I am surprised Mr Cameron has not learnt his lesson after the reduction to 45p in April undermined the Government’s “all in it together” mantra. Perhaps he has been swayed by George Osborne, who is convinced that lower taxes cuts can generate more revenue after seeing that happen with corporation tax on business.

Perhaps Cameron the moderniser will reappear during the election campaign. Yet floating voters might be confused by then. The Prime Minister will abandon the centre ground at his peril. As their own version of his little black book shows, the Lib Dems will be better placed to colonise it after five years in government.

Leaders should support 11% pay rise – everyone knows what happens if you pay peanuts

Few politicians come out well from the saga over MPs’ pay. David Cameron opposes the 11 per cent rise proposed by the Independent Parliamentary Standards Authority (Ipsa) but can’t quite bring himself to kill it off.

Most backbenchers want to see their salaries rise from £66,396 to £74,000 in a one-off uplift in 2015 but only a few have the courage to say so in public.

Ed Miliband takes a tougher line than Mr Cameron, enjoying the luxury of opposition. Mr Cameron and Nick Clegg would probably do the same in his shoes, but mud sticks in government. Gordon Brown (right) was damaged by the MPs’ expenses scandal even though it was beyond his control.

Mr Cameron makes veiled threats to abolish Ipsa, which would take us back to the discredited system of MPs voting on their own pay – and increase the risk of a return to expenses scams when salaries were inevitably suppressed. Full circle.

The three party leaders should stop playing to the gallery, bite the bullet and support the 11 per cent rise. If MPs’ salaries fall behind, the calibre of people entering politics will suffer. This matters: today’s backbenchers are tomorrow’s ministers and prime ministers.