How many MPs work in the House of Commons? About half of them. It's not that the other half are lazy, just that they may be too busy changing lightbulbs. We all knew how many policemen it takes to screw in a lightbulb (none. It turned itself in); how many lawyers it takes (one, but he'll bill you for five); how many conservative economists (none, Adam Smith's invisible hand does it); how many shop assistants (just the one, but only if you have the receipt); and also how many surrealists (fish).

Until now, we had assumed that politicians never changed lightbulbs, because they preferred to keep us in the dark. But it turns out the real answer, according to the body responsible for the day-to-day running of the Commons, is that it takes just the one MP — provided that this MP diligently follows ten key steps when confronted with a broken lightbulb in a Commons corridor:

(1) Put on protective gloves; (2) Wear protective mask; (3) Open sturdy box; (4) Pick up large fragments and place in sturdy box; (5) Sweep up splinters using stiff card; (6) Clean area using damp cloth; (7) Place damp cloth in sturdy box; (8) Seal sturdy box using tape; (9) Label contents of the box; (10) Take sealed box to waste removal area and pass it to a waste disposal contractor.

So how many government ministers does it take to unmask the identity of a lavish donor, or to rescue Northern Rock, or sign an EU treaty at the same time as other EU leaders, or to ensure discs containing confidential details of millions of Britons don't get lost? Answer: Are you crazy? Do you imagine that MPs have time for all that when so many lightbulbs need changing?