There was a set of the £1000, £5000 and £10000 sold a few years ago for $2000 (or at least listed at) in the large plaque/jeton sale that were mainly Crockfords and the Curzon House but also a few others too. There is also a £500 in the set which I think is the rarest of the ones known.
As I 'm sure you will be informed, there were 2 runs of the plaques. If I remember rightly, the £1000 is the scarcest of the other 3 that were sold.
Personally I believe the "Sporting Club" to be the previous name of the Knightsbridge Sporting Club which added the Knightsbridge part due to the International Sporting Club being opened (and maybe, so no confusion, with the Victoria Sporting Club too) mainly because there are no pre-decimal items known from the KSC. It would be great to be able to confirm it one day.
I was asking £300 - £400 for my £10000 (that I still have along with the £5000) but no takers/interest.
Hope that adds a little more info to what you will be told here.