vonrall

Looks pretty granular on the back like sand casting. The owner should be able to tell just by handling it if it's a casting or a stamping.

I don't recall anymore, it was 30 years ago but it was cast and it was the 27th. They sold them at the gift shop behind the Lion monument. However, I have owned some original French Napoleonic plates over the years including battlefield excavated ones and they were all thin sheet brass stampings. Yours looks like a heavy casting from what I can see in the scan although I could be wrong. The headgear of the time was surprising light weight due to the fact that soldiers had to wear it all the time, which is why ornaments were generally thin stampings. A British Grenadiers cap of the warrant of 1768 only weighs about 1.4 lbs total. You should show the pictures of yours front and back to some experienced collectors of this material for verification.

I believe most of these were stamped not cast. In the 70s when I visited Waterloo I bought a repro cast plate of the 27th just like yours. If yours is cast you might want to get it checked out with someone who really knows these kinds of plates.