I have a 1980 series 3 land rover. Every year it needs work. I wouldn't like to think what kind of mess she'd be in if I left her for 27 months without being tested.
VOSA recently changed the rules here for older vehicles. I have a mate who has a 1958 series 1. It's been modified and has a 3.5 v8, he doesn't need to get it tested. Ever. It's a freaking death trap.