Here's the relevant section from the agreement:
"We will 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 a draft motion by December 2010. It is likely that this will advocate single long terms of office. It is also likely that there will be a grandfathering system for current Peers...."Compare that with other phrases:
"We will bring forward early legislation to introduce a power of recall...."We will introduce a Freedom Bill.""We will scrap the ID card scheme, the National Identity register and the ContactPoint database, and halt the next generation of biometric passports..."Elsewhere in the document, changes and legislation are clearly defined in terms of action. I think that the framers of this document knew exactly how divisive this particular element was likely to be, so to ensure agreement, it was left deliberately vague. You can read that as a commitment to move things forward to legislation, but that's not what it actually says - it only commits to taking things as far as a draft motion, not support for actual legislation, although that stage would logically follow. The programme motion is a process, rather than a policy issue.
This allows each side to argue that they are in the right and to read into the agreement exactly what they want to find, but in the most technical sense, I think the Tories have the stronger case.
However, they might find themselves hoist by their own petard, when it comes to a key part of their own legislation, the gerrymandering of the electoral system. The agreement promises the following
"We will bring forward a Referendum Bill on electoral reform which includes provision for... the creation of fewer and more equal sized constituencies"That, the Liberal Democrats have done. Nowhere does it promise that they will be required to vote for the outcome of the Boundary Commission's deliberations when they come back to the House.
These changes are controversial, even putting aside the aspect where it is being fixed to suit the Tories (and even before we consider the further changes due in the next parliament, which will further fix the system). While Labour is the main target, the Liberal Democrats actually suffer the worse in proportional terms and there are even a few Tories who face having their seats abolished. Kicking the proposals out might get more support than they think.
The turkeys may have voted for Christmas, but they don't have to agree to be stuffed.