Things are beginning to look distinctly dicey for the flotilla of big government bills before Their Lordships, leaving aside some close run votes on the Welfare Reform Bill earlier this week, in which defeat was averted by two or three votes.

The assumption is that most of those bills have to be processed through the Upper House by the end of March, to avoid election purdah, the Easter Break and be safely onto the Statute Book before the parliamentary session ends. But do the arithmetic:

On present plans, peers are expected to spend four more days in the New Year on the report stage of the Welfare Reform Bill, eight days on report for the Health and Social Care Bill (on the slightly heroic assumption that its committee stage is completed before Christmas), seven days on the Legal Aid and Punishment of Offenders (LASPO) Bill, and two days on the Protection of Freedoms Bill. So that's 21 days of detailed legislating to be slogged through - before any allowance is made for slippage.

There are ten and a bit weeks of Lords sittings before the Easter Break - 52 scheduled sitting days. Already things look a little tight, but wait - normally Their Lordships spend three days a week on legislation and devote one day a week to other debates - on reports by their select committees, issues raised by individual peers etc. So now we're down to around thirty legislating days - with 21 already spoken for. And I have not got round to counting in the Third Reading stage for these bills - and some of them are so big and so contentious, that they may require more than one day of debate.

And this doesn't factor in any time at all for the Scotland Bill. This gives new tax and spending powers to the Scottish Parliament, and has opponents from the unionist and nationalist perspectives laying ambushes for it, should it ever re-appear after being shelved last April - which I rather doubt.

Add in time needed to debate the Budget and other set-piece events, and it's clear the government has an eye-wateringly tight timetable to enforce. There are some possible get-outs. One is that the House sits earlier to cram more detailed debate into its sitting days - this has already begun to happen and will doubtless continue. Second, backbench debates may be crowded out for the next few months, to be replaced by more heavy-legislating on Thursdays. Third, the House may sit more often on Fridays. None of these options will be popular with peers. To put it mildly. And then there's the possibility that the parliamentary year may have to drag on beyond its expected termination in early May. I've even heard murmurs of a late May prorogation, followed by an early June Queen's Speech, if things drag.

But remember, the emergence of a firm deadline for the end of the parliamentary year empowers their Lordships. Big bills which are not passed when the music stops are lost, so if the Lords insists on changes to the Health Bill or the Sentencing Bill or whatever, it has the Commons over a barrel. We could be heading for a very messy and acrimonious end to the parliamentary year, with much collateral damage to cherished legislation.