So that was it.
About a couple of hours later we saw another (same one?) going the same way (East) and about 2/3000' higher than the first.
Why wasn't the gear raised the first time it came over, would this be due to some tests that were being carried out?
We had a 20-over Cricket match yesterday evening so much of my time was spent spotting. I just added that as I don't want anyone to think I hang arond Croydon with my notebook