It's like a maze, Ian, but I did find this bit:-
The above is from the government's website here
Obviously no idea if your item is over 100 years old, and quite how they draw any meaningful conclusion about whether it's part of a collection or a collector's piece, I've no idea. All items of numismatic interest are potentially part of a collection, so I've no idea what they mean. Nor do they state what the reduced rate of VAT actually is.