Neither of those flew on the UK airshow circuit, Tim.
I suspect that he means an extra airframe used for spares by HAMM/Airpower Inc/Air Platforms Inc. at Lakeport, who operate two ex DERA raspberry ripple B6 Mods - XH567 and WT327.
I wonder whether he means another of the ex RAE/DERA aircraft - WT333, or most likely XH568.