That most mysterious of Westminster rituals

To an outsider the annual end of term bout of parliamentary ping-pong is one of the most mystifying Westminster rituals. It's a high-stakes legislative game, often carried out at the dead of night, with MPs and peers succumbing to their tribal loathing….of the other House.

As an aid to the bemused I offer this cut-out-'n-keep guide to what's going on.

For a bill to become law, both Houses of Parliament have to agree on its exact final form…. So when a bill that has passed the Commons is amended in the Lords, it is sent back - pinged - to the Commons, once their lordships have finished with it, for those changes to be approved…or rejected. This gives rise to items on the Commons Order Paper with titles like "consideration of Lords amendments".

MPs can either agree to the changes (and the government does make a lot of amendments to its own bills in the Lords) or they can reject them, and send - pong - the bill back to their lordships.

If they reject Lords amendments a "reasons committee" repairs to a small room behind the Speaker's Chair, where a message to the Lords setting out the reasons for the Commons decisions is composed in formal parliamentary language. It doesn't usually take long.* They can simply disagree, they can amend the Lords amendments or they can offer other amendments instead.

The Clerk of the Commons, Robert Rogers, quotes an example of the kind of message** carried from House to House as this process unfolds…this was from the ping pong on the 2005 Prevention of Terrorism Bill.

Concentrate…

Another little nuance is the colour coding…extra green pages are provided in the text of a bill for amendments to be added. Amendments by the second House to consider a bill are printed there, in black. Amendments to those by the first House are added in red, amendments to those are added in green, and so on, through violet, brown, blue, yellow, pink, cyan, silver, indigo, gold, light green, orange and dark grey…. So far no bill has bounced between the Houses more than 15 times, but one constraint on the process might be finding a different ink to signify the exchange of amendments.

And so it goes on. The Lords, in their turn, then decide on their response. Do they accept whatever the Commons has decided, do they reject it, or do they offer some new amendment? Another ping, followed, quite possibly, by another pong. There is no limit to this process other than the impending end of the Parliamentary year. And a bill which is not agreed upon falls, when the music stops.

Which is why, as the deadline approaches, both Houses often end up sitting late into the night, convening, sending messages to the other House, then adjourning to await the response. Old hands take the precaution of bringing in toothbrushes and fresh clothing. Recently, the party groups in the Lords have taken to showing movies - Skyfall and the Spirit of '45 are recent examples - to keep their troops entertained while negotiations and manoeuvres take place behind the scenes. The annunciators are scanned for details of the next sitting, and carry the Kenneth Williams-esqe message "House Adjourned During Pleasure".

Most Parliamentarians want their outstanding business dealt with by Thursday. So far, the government has compromised on its proposed relaxation of planning regulations for home extensions, in the Growth and Infrastructure Bill…but another battle looms over its "Shares for Rights" proposal, which the Lords rejected in March, and the Commons reinstated last week, and the Lords rejected again on Tuesday. Will they go another round?

Then there's the Defamation Bill - where the Lords got their way on the "serious harm test" requiring that companies would have to prove substantial financial loss, or at least the likelihood of it, before they could sue for libel. Will peers press their luck further, and insist that private companies running public services should also lose their right to sue for libel? Or will they end the battle there? As the deadline looms, their lordships' leverage increases. And ministers can't even threaten to reform them anymore.

* Arguably the most historic meeting in the Reasons Room was not anything to do with ping pong, but the ad-hoc gathering in March 1963, in which the then Minister for War, John Profumo, was quizzed - in pretty basic terms - by senior colleagues about his relationship with Christine Keeler, and denied any impropriety. That denial was untrue and was later repeated in the Commons, sealing Profumo's political doom and doing huge collateral damage to Harold Macmillan's government.

**quoted from Order! Order! A Parliamentary Miscellany, by Robert Rogers.