BTW my understanding of why the UK does not have retail margin accounts is two-fold:
1) There is no "stocks" culture here. It is only a very small minority of the population who plays in the markets. This goes back to the class system ...
2) Apparently, because a margin account involves borrowing against "physical stock", this means that a whole raft of consumer legislation gets invoked. Which most brokers don't want to deal with. Whereas, because CFDs and Spread Betting are purely "virtual", it is all much simpler.