The House of Lords’ role is back in focus with the Rwanda Bill. Reforming the House has been permanently on the agenda since the last major change in 1999, abolishing most hereditary seats.

Lords reform has never been quite interesting enough to get done. Labour and the Liberal Democrats want the House to be elected. The SNP want it abolished. The Conservatives have seen no need to change it at all while in office.

Before deciding how to reform it, or abolish it, it is worth asking: what is it for?

There are two important functions.

The House of Commons’ highly partisan politics make it fairly hopeless at carefully reviewing legislation. The Lords have more time for this and their relative independence helps them do it well. Many peers have no party link but often have serious expertise or experience - in science, defence, law, community organisations, diplomacy, business. Even political appointees, often with useful specialist knowledge too, are far less responsive to party discipline than MPs. Lords amendments are not often accepted by governments. But their amendments are often seen as sensible and governments often make their own amendments reflecting the criticisms.

The other function, which we may soon see demonstrated, is challenging poorly thought-out or knee-jerk legislation which has been rushed through the Commons. In the UK, with no single written constitution, a Government with a cohesive Commons majority can do whatever it likes through legislation - except for the existence of the Lords. The Upper House’s power is limited. Legally, it can only delay Commons legislation for a year. By convention, it won’t usually block Commons legislation completely, respecting the Commons’ democratic legitimacy. But delaying thoroughly bad legislation - holding it up to the light and saying “Really?” - often makes the Government think again, more carefully. It is one of our few safeguards against democratic absolutism.

The embarrassing political appointments of recent years have given the Lords a bad name. But they are still only a small proportion of the membership. So far, they haven’t been numerous - or active - enough to break the delicate balance that usually makes the Lords/Commons relationship work.

Many argue that electing public bodies is the only respectable way. But it does depend on their role. We find it odd that some American states elect judges and prosecutors. It is not clear that the Lords’ limited role would be done better by an elected body. If elected, they would be as partisan as the Commons, adding little value as a revising chamber. And it would risk deadlock as its new legitimacy increased its authority and confidence - even more so if elected by proportional representation, giving it more legitimacy than an unreformed Commons.

By all means improve the appointments system. Get rid of the now discredited personal patronage of Prime Ministers. Adopt the Lords’ own proposal of 15-year term limits. Even elect it only partially. But don’t remove one of our few constitutional safeguards by adopting a system that more or less clones the House of Commons.

George Fergusson is a retired senior diplomant