Looking up things for a fic I found a couple of really useful site with information about UNIT.

http://www.whoniverse.net/unit/ (Fan made one with loads of information collected and arranged by year)

and http://www.unit.org.uk/ (BBC made - as far as I can tell - to tie in with the relaunch of Doctor Who in 2005)

I eventually found what I was looking for, Department C-19 http://www.whoniverse.net/unit/C19.php Which is who Johnson will be working for if/when I get round to writing the plot bunny posted yesterday.