I don't regard myself as anyone who actually wins a lottery (or even a raffle) so I don't expect this to be worth much but I thought I'd ask what the experts thought of this item.

I asked about this a few years back but didn't follow up, I just came across it again in my games draw so thought I'd try once more to find out if this is worth anything.
Despite claims of 'only 20' I don't think this type of buckle is particularly rare.
Provenance-wise I DM'd for TSR UK at GamesFair Open Championships from 1982 to 1989, the DMs would gather at The Mill, Cambridge before each tournament to go through the module and agree our approach to running the game. After one of these events we were asked to grab anything we wanted from a goodies draw and I picked this belt buckle. I never wore it. It has resurfaced 30+ years and 3 house moves later. Yes I am a pack rat. If any of the old AD&D tournament crew are on here they might remember I was the one who one who won the 'Nit-Picker Of the Year' award for overzealous proofreading of the module manuscript.

If no one knows what I can do with this then its back into the draw for another decade or so.

I'll attach links to photos from all angles as I understand there are a lot of forgeries.  

Thanks
Mark

Thank you Frank, much appreciated
Although my Brexit friends would have a fit if I sold it for Euros, just Pounds Sterling over here and I wouldn't be surprised if there's a campaign to reintroduce the Guinea, Shilling and Farthing soon.