I was reading TfL's website (part about commercial photography) and
have an idea: what about several railfans buying several hours of
"shooting" time together? Since the total cost will be split (I think
groups of up to 5 persons allowed), it won't be too expensive. And
among interesting locations there are Charing Cross (I suppose the
Jubilee one) and Aldwych. Also looks like it could even be possible to
shoot from the driver's cabin (only two persons at a time though) -
I'd love to go around the Inner Circle this way ;-)

Anybody tried that?