Watch List notes:

G Elizabeth II, 2018 United Kingdom Gold Proof Commemorative Coin Set, comprised of five pounds; two pounds (3); fifty pence, head r., wearing tiara, rev. various (S.PGCS29), in case of issue, with certificate, FDC (5)
Set 152. The Standard Catalogue lists 139 sets issued, but this is clearly an error.

Estimate: 4250 - 4750 GBP