D120A,
Apologies, you are so correct - it was indeed '55.
You must be extremely knowledgeable. I presume B of B was a Battle of Britain display somewhere - Bristol area? Neither flight that day was very long and I recall my father stating that the Ashton's endurance was limited and could catch the unwary out.
How do you know when the Britannia was first registered? G-INFO certainly does not hold that data.
A worthwhile digression
If the thread continues, perhaps I'll post one or two of his other EGLL visits!