Section5's 'sped up house with proper basslines' is probably as good an explanatiopn as you'll get. Not sure if this is really answering the question but here's some of my thoughts. One thing I associate with pre 97 UK garage is a sound that is (i think) reffered to as organ stabs. It's present in one of the earliest UK tracks, 24 Hour Experience- Together
And is even more important in this excellent Cheese & Pickle Ep track, at the 2:45 drop
If I had Ableton Live I'd do a compilation of those organ bits, they're great.
The problem is these type of effects happen in american tunes as well, I'm sure I've heard them in Masters At Work tracks. Which sort of demolishes my argument I suppose, but still. Simon Renoylds would probably say that the rushtastic Cheese & Pickle track is the product of someone exposed to the UK rave scene, not a smooth New York DJ who's never taken a pill and doesnt know anyone who has. But then you have to explain all the American producers who influenced the UK scene. Mark MK Kinchen, Tina Moore, Armand Van Helden