The debate about how Birmingham should be governed has been simmering for years. It appears clear that it will never be resolved until the city’s residents are given a choice on whether they want an elected mayor or not.

That’s not to say that the city would necessarily vote for an elected mayor if a referendum does take place. There are powerful arguments in favour of creating a high-profile and accountable leader, but there is also a strong case for sticking with a cabinet model where authority is shared, to some extent, between a council leader and his colleagues.

But Sion Simon’s decision to quit Parliament in order to campaign for the post has certainly thrust the issue into the spotlight. And as the first confirmed candidate for the position, he has at least shown willing to back up his support for the idea of an elected mayor with action.

Mr Simon’s announcement is a huge gamble. He’s giving up the life and salary of an MP and, for the time being at least, being a Government minister, in the hope firstly that a mayor will be created; secondly that he will receive the Labour nomination, and thirdly that he will see off other party candidates and independents to win the top job.

He didn’t need to stand down from the Commons. Boris Johnson campaigned to become London mayor while he was still an MP, and voters probably don’t expect candidates to resign from their existing jobs before they have been chosen for a new one.

One tends to assume that he must be confident of at least winning the support of his party to become Labour’s official candidate, but it’s early days yet and there’s plenty of time for a challenger to emerge.

It must also be said that the announcement looks very much like an admission that the Conservatives are on course to win the General Election. Labour supports mayors, but introduced a cumbersome procedure for introducing them which forces proponents of the idea to collect thousands of signatures before a referendum is held.

Conservatives, by contrast, have simply said they will hold a referendum in Birmingham come what may. Mr Simon insists he expects Birmingham to create a mayor whoever wins the election, but it does appear that he is far more likely to gain his wish if David Cameron is Prime Minister.

Much will be made of his expenses claims, and the fact that he is repaying £21,000 he received from the House of Commons to rent a flat from his sister.

That’s a reasonable point, but suggestions that this may explain his decision to leave the Commons don’t stand up. He’d be much better off avoiding the limelight as a backbench MP if he was embarrassed about his expenses.

Nonetheless, Mr Simon has proved to be a colourful character, and will struggle to live down his YouTube appearance, in which he mocked David Cameron. Whether this will help or hinder his campaign remain to be seen.

What he certainly deserves credit for is having the guts to announce his candidacy.

And Mr Simon is right about one thing – if he wants to be mayor, it makes sense to lead a campaign to create the position in the first place. Other potential candidates should take note.