judging from today's evidence, it's clear that the Lib Dem brakes on the Tories are as effective today as they were back in the distant days of May 2010.
In just three hours, we've had three different examples today of the way the Libs are constraining Tory ambitions.Those examples were the abolition of the 50p tax rate, the passing of more laws against strikes and the implementation of Lord Beecroft's proposals to make it easier for employers to sack people.
Now don't get me wrong. I love upsetting the Tory right. Seeing my party stopping its cherished plans being put into practice gives me great pleasure.
But there are two reasons why the Liberal Democrats need ambitions beyond this.
The first is that by thwarting their right wing we are helping the Conservatives.
The right, of course, are convinced that their ideas would be wildly popular. It is one of the paradoxes of politics that the more extreme people's views are the more inclined they are to think that the bulk of voters support them. This is why Conservative Home has called its campaign against Cameronism "majority Conservatism".
But, as Michael Heseltine observed of Beecroft's ideas, "You don't want to make life rougher and tougher for large numbers of people you want to vote for you."
So by blocking the loonier ideas of his right wing we are helping Cameron's popularity with the voters and thus his chances of winning the next election.
The second reason why blocking the Tory right is not enough is that the Lib Dems should have positive achievements of which to boast from five years in government.
So let's point to the taking out of tax of low earners, extra funding for poor pupils or some of the other policies from our manifesto that we have been told are being put into practice.
Because if the voters are that keen on stopping the Tories doing too much come the next election, they may decide that the simplest way to bring that about is to vote Labour.