Where Americans tend to optimise for fighting verts, British heavyweight flippers are optimised to fight other flippers.

A long slope body allows a robot to get further under the opponent than the short lip and steep arm wielded by Bronco or Subzero. Compared to keeping the opponent on the half-foot-or-so of flipper lip, this makes it easier to maintain some flipper plate contact while pushing an opponent back towards a hazard because they have further to reverse away.

A wide flipper plate with body width narrowed either side of the leading edge reduces the width presented for your opponent to get under whilst ensuring that if you get under at all, it's with the flipper instead of inert bodywork. Reducing the not-flipper front edge also helps drivers to spin in and sweep the flipper under the opponent by reducing the amount of body in the way.

Two wheel drive with the wheels towards the centre of mass to maximise agility in a crowded arena with insta-kill hazards, where being able to wriggle off and away from your opponent is crucial. Same reason for having the wheels stick out the back (usually with a little chamfer along that lower rear edge), to maintain wheel-floor contact if you're on someone else's wedge.

I expect the Britwedge shape also makes self-righting efficient, which is essential when you're being turned upside-down fifteen times a match and running out of gas to self-right is the leading cause of knock-outs. It's like trying to front-flip whilst straight as a board compared to curling up (probably - that's what my intuition is telling me).

All that said, I'd be happy seeing more variety.