If modelling the current UK rail network is your thing then you might find this an interesting prototype to add a little variety to your layout.
This was photographed this morning from our bedroom window. Initially it was hovering and I would have got a decent (in focus) photo but by the time I'd grabbed the camera it had started to move. Strangely it wasn't hovering over the railway (which is at the back of the house) but somewhere off to one side which is why I could see it out of the front bedroom window, so I've no idea what it was actually looking at.
Apparently this particular helicopter, call sign G-NLDR, was introduced as part of a new contract that started on the 4th of December 2013 and which runs for five years. It would certainly add something different to a modern image layout.