That’s a very interesting article. It confirms my suspicions that city (and probably borough) mayors have taken credit for things they had no real hand in. That applies to all of them, by the way, irrespective of party.
I’ve long thought that the newer mayors and the city halls are a waste of money. I bet London and Manchester would be no worse off if Livingstone, Johnson, Khan and Burnham had never had a job to fill. I certainly don’t believe that any significant transport authority is better run by a mayor.
Burnham looks to me like a smoke and mirrors politician. That joke upthread about three brands of Labour walking into a pub in the form of Burnham sums it up nicely.