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jno, so he is responsible for ythe day to day running of the police in London.
//. As such, the Mayor is responsible for setting the strategic direction of policing in London through the Police and Crime Plan.//
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As explained by ellipsis and jno, danny, I think you are confusing strategy and tactics. Strategy is "we will make a cup of tea for all the team at 3pm every day". The tactics are "We'll fill the kettle and switch it on at 2:45. We'll get the cups from the cupboard and mild and sugar them at 2:50 etc. etc."
The Mayor decides that tea will be provided every day at 3pm. The Commissioner decides what time to put the kettle on, etc.
Having said that, the Commissioner would probably devolve the task to a Commander or Chief Superintendent. He or she would look at the pay and working conditions of the people picking the tea and decide they ere unacceptable so no tea could be purchased. It would make no odds anyway because anyone asking for white tea would be branded a racist. They could go and play chess instead, but that's under investigation as well because white always goes first:
https://www.dailymail.co.uk/news/article-8450553/Chess-master-blasts-ABC-wasting-taxpayer-money-debate-game-racist.html
Draughts must be OK, though, because traditionally black opens the proceedings.