I had a look and that's exactly what I was after - the only problem as
you say is they will come out at nearly 50 quid each with VAT and
postage.

Hmmm what to do - I guess there's only 2 places I'd use them on the
top and bottom landing. The alternative is a £5 PIR designed for
outdoor use like the one I have set up in the kitchen which works
fairly well.

I think I should probably spend the cash...