Now either I'd struck philatelic gold or I'd acquired a handful of forgeries. Generally I assume that if something appears too good to be true, then it's too good to be true. So I left them for a few years before examining them closely. It was obvious to me that the number ten in the corner of the violet stamp was a bit funny. It appeared to be superimposed on a slightly darker disc of purple. So I felt that this had probably been tampered with.
I took the other two to my local, friendly stamp dealer - Ron at the Enfield Philatelic Centre. He looked at them under a glass and told me that they had both been altered. If I look carefully at the middle stamp, I can see that the number two does indeed seem to be slightly flattened at the top. It just doesn't look right.
But the third stamp - the one shilling - looks OK to me. I've checked out similar stamps online and I can't see any real problem. Ron is very knowledgeable, but it is conceivable that he might be wrong.
I'm a member of the Royal Philatelic Society, and they have a committee of experts who have all the latest equipment and years of expertise. They can judge these things. Because I'm a member I can get a couple of stamps checked out free every year - I have to pay a handling charge of about £10 per stamp. so I think I might just put it in for checking. If it's no good, I've lost £10. If it's good then the value of my stamp collection will have multiplied overnight.