Portsmouth At Night, a huge group of like minded urban photographers
that like to shoot at night.
www.portsmouthatnight.com

Yup, I answered my own question by wandering through a few more pages of
your photos on flickr - one had a title that gave the game away.

Some very impressive shots there may I say!

Impressive? Did you see the "first venture into portraits....."? Work
of a natural genius I reckon.