[petesergeant]

That's not inconsistency in the rules, that's inconsistency in what being the mayor means. In Sheffield it means you show up wearing funny clothes every so often, in Greater Manchester it means you have a full-time job, a large budget, and actual responsibilities.

For our American brethren, it's like the difference between being the Mayor of NYC vs the Macy’s Thanksgiving Day Parade King.

[roryirvine]

It's actually the role of Police and Crime Commissioner that prevents them from being an MP simultaneously. In Greater Manchester (and London) the PCC role is combined with that of Mayor, but it isn't in most other city regions.

There's not much actual difference in the mayoral aspect of the roles - Jarvis was the Mayor of the South Yorkshire Combined Authority, not simply the mayor of Sheffield City Council.