A MkII Hoverhawk, from 1969. Heavily restored and updated at the museum, it now features the gas turbine APU from a Harrier jump jet, which should give it rather spirited performance. Land and sea testing are due to begin in 2020.
An American-made Hovertechnics Hoverguard 800. These were stationed at Heathrow airport in case an aircraft had to ditch in the marsh near the runways. They would rush out and deliver life rafts to the survivors.
Though not put in production for the Royal Navy, Iran bought six in the 70s. It's widely assumed these are stored or scrapped due to their age and the inability of Iran to get spare parts due to trade embargoes.
The control cabin for Princess Anne is off limits, but adjacent is the nearly identical control cabin for the Swift, the second SR.N4 built. Upfront would be a pilot and a first officer, who doubled as a flight engineer.
This is also an SR.N6, but an evolution of the original design with two smaller props instead of one big one. The smaller props, in this case, producing less noise than the single larger one. This is the oldest operational hovercraft in the world.