Most Metropolitan Police Commissioners could echo the words of Sir Harold Scott, the first postwar commissioner. In 1954 he said " We in this country can count ourselves lucky that the police have always stood outside the political scrimmage". In other words "we run our own show". I suspect the French Interior Minister exercises more control over the CRS riot police than Jack Straw does over the Met.
It was not always so. Much of the nineteenth century policing was locally controlled by elected committees; the police in Scotland are still run by committees of elected local representatives. If, for the last 40 years, we had had a GLC with a police committee of elected councillors (without magistrates, please) running the Met, there would have been no need for an inquiry into Stephen Lawrence's murder: he would probably never have been murdered.