Who? Yes, they are well reputed too (established 1666) but they won't be able to do much from a photo, they'll want to feel it! There's also some bloke in Wales, I forget his name (funny bloke, had the hump with me over some silly copyright issue, I forget the details now). He knew his stuff though, used to be the Queens Assay Master. Have a google for 'Coin authentication' and when you find a website that looks like it was made by an 8 year old....you've found him