I'm not entirely sure why Zippers haven't been seen in this country - they may have been around in the past but you tend to find them more in the US for some reason.
Zippers are still widely travelled in Australia and America, the ride has a cult following due to it's notorious background and stomach churning reputation
The ride has undergone major safety modifications in recent years with Chance rides making changes to the cables and rollers that were prone to breaking and dropping parts etc, also the door lock systems.
The ride is still very ahead of it's time in the thrill stakes.
There is one in storage in britain still and there is talk of it being brought back out again in fairground enthusiast circles so watch this space, it might just happen