The failure to pass Lords reform will open up more cracks in the coalition, but not cause it to fall.

The threat not to support the boundary changes was made by a, plausibly deniable, former aide of Nick Clegg. Lib Dem ministers are carefully avoiding, at least on the record, confirming or denying what they will do.

However the boundary commissions are not required to report until October 2013. It would usually be a few months after that before Parliament votes on the draft Orders in Council which would implement the boundary review. Who knows what the position will be by then.