Can you spot what's wrong with these Charles and Diana stamps?

A stamp commemorating Charles and Diana's wedding is just now getting some attention, 36 years later. People have spotted something odd about the stamp, and have been angrily commenting about it online.

Can you see what's wrong with it?

How about if we show you some photos of the two in real life?

It's fairly difficult to spot. Figured it out yet?

For some reason they've made Charles a lot taller than Diana, or at least stood him on a box for his stamp.

In most official photos and stamps, for some reason the photographers always seem to make Charles stand on something tall.

Even though they were exactly the same height as each other.

The decision to make Charles tall on the stamps has just been noticed online, and where it's caused some confusion.

It's also led to some awkward and polite exchanges between people on twitter.

And some debates about why they've done it.

Of all the explanations so far though, only one seems to make sense.