Sir George Hifi was a Tottenham Sound System run by Sir George (George Brightly) in the late 70's and 80's.
Sir Geroge had a residency at Cubies Club in Hackney on Fridays and at the Noreik, Tottenham on Tuesdays in 1979. And every Thursday at Shades in Manor House in 1980.
There was also a Sir George the Untouchable operating in the Tottenham area circa 1976, it's unclear if this was the same sound.