Elite private security services liaise with the UK police service - that’ll be business as usual otherwise credible threats may be missed.
Still no reason for Harry to directly hire a UK specialist police service, such as the highly trained royal protection team. Is Andrew using this service or is his security detail paid for out of his own pocket?
Bearing in mind this is a DM report, I see this item as a red herring.
That said, Harry’s name is putrid mud in the rank & file of the UK armed forces - he may be a veteran, but he was a toy soldier & ungrateful with it - & many of the elite private security firms are ex UK services, so it may be that there is no rush to bid for his business. Hence the request to being his US security team over which was declined.
With the Royal Jubilee imminent, maybe he’s looking for someone somewhere to provide security so that he can turn up for the jollies.
Harry, always read the small print & listen to what the men in grey when they say to you if you leave like this, then you are left.