Free Love Freeway,
Once upon a time in a land far, far away there were a brave band of guys and gals who used to live in the bowels of Heathrow tower and provide Thames Radar & Heathrow SVFR.
Then one day during the great autumn of 2003 a mysterious flood occured and drowned the buggers. Those that survived were swiftly rehoused at TC down the end on the left hand side next to their heathrow approach buddies. Many of these tortured souls were also tower controllers but eventually a staff split was devised that allowed the two to function separately (I believe that to be the case, correct me if I am wrong). Sometime around april 2004 Thames officially became part of the TC family (some three years earlier than planned).
All was well in the world, sort of.
Those lovely thames chaps and chapettes do not work when the sun sinks below the horizon as heathrow approach take SVFR at night, and so they were invited to turn their hands to other airports so that they could partake in the great night shift snooze in. I suspect that they have now begun to train on other approach units now but that is the reason that they were initially thames only.
And they all lived happily ever after
The End.
Edited to correct terrible spelling mistake.