Police Numbers

I get very annoyed when people complain that the Metropolitan Police have some 30,000 or so Police Officers, but only about 6000 can be mustered for duty at one time.
Now I worked as an engineer in the aviation industry for many years and for ten or so I was a shift engineer working shifts in order to provide 24/7 cover 365 days a year. We worked a five shift system of eight hour shifts with about half an hour overlap. For those who haven't done the maths, 24/7 equates to 168 hours a week whilst 5 shifts provide 200 hours on the basis of a 40 hour week. The difference doesn't provide much leeway for overlaps, management activities, training etc. Of course, many paper pushers also do a nominal 40 hour week, (9 to 5 or equivalent) but they take an hour for lunch as well as morning and afternoon tea breaks and thus really work less than 35 hours at their desks.  Like the police, my staff had to be available to take action any time during their shift and were lucky if they ever got a proper meal break.
Of course the usual personnel administrative types were for ever wanting to know why it took five staff to cover one post and seemed unable to accept simple maths, and it seems that large parts of the media  have the same problem.
The fact is that Police Officers, like most other employees, expect to work a 40 hour week and to have holidays. And quite reasonably, if they are obliged to work longer hours because of a crisis, they expect to be paid accordingly.
Looking at the figures, if the Met has a strength of about 30,000, it is doing quite well to get 6000 on active duty at one time, as my calculations above make no allowances for leave, training or sickness.