So we have a Tory-Lib Dem coalition. Masses has been written about all the pros and cons of this, and I may return to some more themes in a later post. But for the moment I want to focus on the constitutional reform issues that have been thrown up over these last 6 days.

Yesterday night it looked like all the coalition deal would entail would be a referendum on AV to replace First Past the Post. AV is not proportional (see this for an explanation), so I shrugged and groaned, and feared the Lib Dems had sold out. Then this morning on The Guardian’s live blog:

9.57am: The BBC’s Laura Kuenssberg says that the Conservatives have given the Lib Dems proportional representation … in the House of Lords.

There will be an elected second chamber, voted in using proportional representation, according to Kuenssberg. If correct, that’s another Tory compromise that might not go down well with a number of backbenchers.

This news however does not feature on the BBC’s list of constitutional changes in the coalition deal.

PR in the House of Lords makes things very interesting and – above and beyond the voting system – would fundamentally change the balance of power between the House of Lords and House of Commons. The Parliament Act would cease to work as it does currently as an elected Lords would have gained considerably in terms of legitimacy. An AV-elected Commons and a PR elected Lords would almost certainly create some kind of perennial power sharing arrangement, and a complicated (although welcome) new balance of power between the two chambers.

This sort of issue is at the very heart of any country’s constitutional arrangements and yet, it seems, a deal has been struck on this in a matter of 6 short days. Remarkable (if, of course, it proves to be true).

[UPDATE at 1828]
This is the text of the coalition deal:

We agree to establish a committee to bring forward proposals for a wholly or mainly elected upper chamber on the basis of proportional representation. The committee will come forward with draft motions by December 2010. It is likely that this bill will advocate single long terms of office. It is also likely there will be a grandfathering system for current peers. In the interim, lords appointments will be made with the objective of creating a second chamber reflective of the share of the vote secured by the political parties in the last general election.

The long non-renewable terms part is interesting, hence electing 1/3 of the Lords each time, and for 15 year terms or something like that. Could be interesting.