Section 23 of Coalition Agreement covers Boundary Reviews:

We will bring forward a Referendum Bill on
electoral reform, which includes provision for
the introduction of the Alternative Vote in the
event of a positive result in the referendum,
as well as for the creation of fewer and more
equal sized constituencies. We will whip
both Parliamentary parties in both Houses
to support a simple majority referendum on
the Alternative Vote, without prejudice to
the positions parties will take during such a
referendum.

The Boundary Review had nothing to do with House of Lords reform. It was linked to the AV referendum which the LibDems secured.

Clegg accusing others of breaking promises beggars belief. The LibDems are desperately trying to spin this, but in reality the backbench Tories are the ones to sacrifice political gain for sticking to their principles – however wrong they are to defend the current upper chamber. The prospect of the Boundary Review was keeping the Tories in the Coalition – they were never going to go to the country while it was still in the offing. That lock has gone now…

UPDATE: Just a thought, what is going to happen to LibDem Ministers when it comes to the vote. Will they resign?