Red Kite over the garden

The second Red Kite for my garden (Cromwell Road, Worcester Park) headed high over east at 12:20 today, being mobbed briefly by what looked very much like a Hobby but I can't be certain. Unfortunately this one didn't hang around for a photo. So are these kites migrants or wandering reintroduced birds? Certainly, Red Kite is very regular at Staines Moor nowadays and the Chilterns are not too far away, although I've yet to notice a wing tagged bird. Great to see all the same.