that's it? Your whole thesis that Britain has had ongoing and widespread tightening of gun controls is based on one pro-gun website, which (surprise of all surprises) takes a dim view of gun control? Fuck me with a broomstick.
There is no slippery slope because Britain, like Canada, has ALWAYS had tight gun control. These people want to go UPHILL (shredding the metaphor a bit here) and are pissed because the gov't won't give in.