If Tony Blair had wanted to appease the left of the Labour Party, then abolishing the role of Lord Chancellor was a darn effective way of doing it.

There’s been a broad welcome from liberals to the proposal of disentangling the legislative and judicial functions and to the establishment of a new department for constitutional affairs. Still, you might have thought that Tony could have come up with something a little more substantial than this highly skeletal proposal of a supreme court.

So why now? The idea of a ministry of justice has been kicking around for years. New Labour lawyers have had plenty of time to draw up detailed plans on such a dramatic overhaul, yet insiders say that no detailed drafting work has been done on the proposal. More cynical Westminster observers mutter that if you can’t deliver on the pledges that people really care about – most notably health – then go for something dramatic that you actually can push through.

What’s clear is that Lord Irvine’s resignation unblocked the reform process. He may have been a modernising Lord Chancellor, but he wasn’t keen on abolishing himself – and he certainly didn’t support an independent judicial appointments commission. Irvine’s departure means that the senior lawyers now in Government are a lot more liberal; Lord Williams is regarded as a constitutional radical, for example.

There are plenty of practical issues to be resolved. First, how is the new Department for Constitutional Affairs going to work with the Home Office? Despite the super-chummy way in which David Blunkett and Charlie Falconer were acting last week, Whitehall insiders are still predicting turf wars between the two departments.

The biggest scrutiny will be reserved for the judicial appointments commission. How do you make it representative and accountable without turning it into a televised bear pit? What will be the split between lay and professional members? Will the commission be susceptible to judicial review?

In the meantime, you can sense the relief with which MPs have greeted Falconer’s promotion. His easy manner and robust intellect won him a host of friends at the bar, and he’s winning plenty of allies in the House as well. “He’s a rare bird,” says a Westminster insider. “He doesn’t mind handling the tricky tasks and he doesn’t have much political ambition. And he’s the only person who ever made me late for Prime Minister’s Question Time by ordering another bottle of wine.”