Watch List notes:

(g) Elizabeth II (1952-2022), 'Completion of the Single Market', Commemorative Gold Proof Fifty Pence, 1992-1993, by Raphael Maklouf and Mary Milner Dickens, ELIZABETH II D · G · REG · F · D · 1992, third crowned portrait right, rev. 1992 - 1993, Conference table with twelve chairs around and twelve stars for each of the member states linked by a network of lines of trade and commerce amongst the Community, a larger chair at 12 o'clock shows the letters 'UK' to represent the Presidency of the Council of Ministers, edge plain, 26.23g, 12h (KM 963b; Spink H5 [S.4352]), lightly fingermarked, otherwise brilliant, much as struck and one of only 2,500 pieces issued, very rare thus.
NGC have determined residue on this coin (Cert. #6382915-001). The coin has yet to be conserved
Estimate: £1200 - £1500