What make a good minister? Is it how well they perform at the Dispatch Box in the Commons? Or their ability to field questions on Newsnight? Or even their ability to be a good lunch guest for a member of the lobby? The truth is that often we don’t know whether someone has been a good government minister until years after they’ve left the department and the policies they introduced have actually run their course, rather than just enjoyed a bit of media limelight.

Take the 1999 Teenage Pregnancy Strategy. Launched in June of that year by Tony Blair, the strategy examined a study by the Social Exclusion Unit and aimed to halve the rate of teenage pregnancies in ten years. It set up a national campaign to educate young people about the importance of using contraception, advice on how to deal with pressure to have sex, and about what teenage parenthood was actually like. It also set up a new task force of ministers, an implementation unit led by the Health Department, and an independent national advisory group on teenage pregnancy to advise the government and monitor the success of the strategy.

Today, Tony Blair has long been out of government. Likewise the Health Secretary at the time, Frank Dobson, and many of his junior ministers in that department. But the number of teenage girls becoming pregnant in England has halved in the past 15 years and is today at its lowest level since the 1970s. And the greatest falls in conception rates were seen in the areas that received the most funding from the TPS. And Alison Hadley, who led the 10-year programme, will advise the World Health Organisation on how other countries can adopt similar approaches in lowering their own teenage pregnancy rates.

This is a success that none of those who set up the strategy could preen about while in government because social change takes a long time - and this scheme was given ten years. But it is now working.

Conversely, of course, when things go wrong in government, the people responsible are rarely around to be held responsible - even if their party is still in government, as ministers are moved so often that it’s impossible to work out who was responsible for what. But what makes a good minister, as well as simply time to do the job, is the ability to think about what your policy will have done to people’s lives over a decade later, not whether you’ll get a couple of good headlines the next day, or indeed at all.