Oh, SASLess, you can't bring common sense to play here it is the UK, aviation and the Home Office............
The police forces concerned have been working together for some time to get these aircraft. Most of the 6 are replacements - Cleveland is a special case involving the break up of an existing consortium. They were forced to upgrade because the CAA changed the rules so that they all had to have a SPIFR helicopter (or use 2 pilots) for night flying. They were encouraged to do a bulk purchase. EC said they would do a discount, if they were all the same. As usual the Home office will give a major part of the capital cost as a grant.
The Home Office has made a clear statement of policy on countless occasions that there will be national this or regional that for policing. The Chief Constables and individual police authorities just ignore them.......... But this time could just be different possibly.[But you and I will be retired long before it happens]
But really winches! They might then be useful for a host of things. Except that the CAA will insist on OEI OGE hover capability, so you will have to use children or similar on the winch.
It will be interesting to see how the Met fare with their EC145s, winches and fast-roping kit. I would guess they will eventually beat the CAA into submission, but only as a special case that won't apply to other UK police.
The message from history is try and avoid a series of serious accidents when you introduce aviation into your operation. Otherwise you will get the Feds crawling all over you. The rest of Europe seems to do fine with the police operating state aircraft, but not here for now.