Jersey is one of the UK’s tax havens, so you do get a fair number of Jersey registered cars on UK roads, usually driven by someone who’s dad had a ‘creative’ accountant.
The original ones were made for the German army and police, and those ones are perfectly serviceable off-roaders, similar to a Land Rover or Jeep. Then at some point Mercedes realised they could also sell them to rich people, and the gradually morphed into the luxo-barges they are now. (Although I suppose the same could be said of Land Rovers)
