Nick Clegg (and Lord Strathclyde's) road to reform

Nick Clegg bounced into the committee which was established to monitor his constitutional reform agenda in surprisingly cheerful mood, with no visible bruising from his and his party's pummelling by the voters last week.

There were flashes of rueful humour about the defeat of AV in the referendum, and no apparent wavering over his (and the Coalition's) commitment to revamp the House of Lords.

Perhaps the DPM's chirpiness was because his Conservative partners in government have just been painfully reminded that, whatever happened last Thursday, the parliamentary arithmetic hasn't changed. They still need Lib Dem votes.

The House of Lords has provided two object lessons on this point this week, first defeating the Government on the Fixed Term Parliaments Bill, and then, last night, filleting out the elected police commissioners from the Police Reform and Social Responsibility Bill.

It's an object lesson - the only way the Coalition can be radical on anything is if both sides work together and keep their dissenters in line. And that applies just as much to Lib Dem proposals as to Conservative ones, which Nick Clegg will have to bear in mind as the good ship Lords Reform prepares for launch.

Shortly after his proclamation of a new "muscular liberalism" and hours before the rebellion last night, the Lib Dem leader was communing with his noble friends in the Lords, at their weekly meeting. But his dabs don't seem to be on the defeat last night, which was engineered by sceptics with genuine doubts about elected Police Commissioners - and at the Committee today, he didn't equivocate for an instant and promised that the Commons would, in due course, overturn the changes made by the Lords.

It's no great secret that the Libs reluctantly swallowed this Conservative manifesto proposal as one of the necessary compromises to forge the joint policy platform set out in the Coalition Agreement. They want more accountable policing, but through a less radical mechanism - elected police authorities, not a single law 'n order supremo.

And the effect of removing the central proposal from the Bill on the first day of committee stage consideration is to rule out more modest compromise on the Commissioners - since they're not in the Bill any more, there can be no amendments in the Lords to place checks and balances around them. So if the Commons asserts itself and tries to put the Commissioners back in the result may well be something less nuanced than might have been produced by Lords amendments.

What I'm working round to is that both parties have to stick by their grand bargain in the Coalition Agreement if either are to achieve any of their objectives. And listening to Mr Clegg's Conservative sidekick, Mark Harper, he did not sound any less committed to revamping the Upper House than the DPM.

There will be a special joint select committee to scrutinise the Coalition's draft proposals, and when legislation follows, the Lib Dems want the Conservatives to take the lead - so that the Leader of the Lords, Lord Strathclyde, will have to bite the bullett and seek to persuade his peers, mostly opponents of change, to swallow it. Mr Clegg in his turn will pay the necessary blood price, including whipping his troops to reinstate the elected police commissioners.

This will be an uncomfortable process for both sides - and the expectation is that, on almost any given issue, guerrilla groups from one fringe, or both, will rebel. But that is precisely why the Coalition's comfortable majority is so essential.