1851 AD., Great Britain, International Exhibition, Brass Medal, BHM 2443.

Great Britain, International Exhibition. by Messrs R. Heaton & Sons, 1851 AD.,
(silvered) Brass Medal (23 mm / 4,65 g), small hole on top,
Obv.: VICTORIA QUEEN OF GREAT BRIT. , head of the young queen Victoria left.
Rev.: THE CRYSTAL PALACE / LONDON 1851 // PROPOSED BY / H. R. H. PRINCE ALBERT , the huge building known as the Crystal Palace (expo building) and surroundings; in field above, black ink, written collector´s number: 10.
BHM 2443 AE RRR, not listed in brass, silvered or not .

thanks to "constanius" for the reference