I bet you're not far off the mark there Urban.
There was an underground market in the centre of Manchester (gone now) called Oasis. It was a place where scallies went to buy cut price sportswear.
Found this;
FOTT FORUM : Sneakerfan - Noel Gallagher
GA - Cos the guy who ran the Oasis shop was a City fan wasn't he?
NG - He was yeah, that's where I claim we got our name from. Liam always comes up with another dull story that he saw it on a poster somewhere, and it's like "Shut up man." But that was a wicked place to go, we used to wear these levis yellow checked shirts, they were yellow with like a sort of red check, brown wrangler flared cords and any adidas you could get, Nike didn't even exist then.
I can shed a bit more light on Dexys Midnight Runners too.
Apart from the obvious Dexy's bit mentioned in Predator's link (dextroamphetamine) which was used by Northern Soulers as the drug of choice.
The Midnight Runners part is a euphemism for energetic all night dancing. In particular at the allnighter soul clubs in the north of England... 12 midnight till 8 a.m.
Hence, Dexys Midnight Runners.