Watch List notes:

Elizabeth II (1952-), gold proof Fifty Pence, 2017, struck for the 375th anniversary of the birth of Sir Isaac Newton, crowned bust right, JC below for designer Jody Clark, Latin legend surrounding, ELIZABETH II D. G. REG. F. D. 50 PENCE, rev. design by Aaron West, an interpretation of Newton's Proposition 11 from Book One of Principia Mathematica, accompanied by the inscription 'SIR ISAAC NEWTON' and the denomination 'FIFTY PENCE', weight 15.50g (S.H39). Brilliant proof as struck with original Royal Mint box and certificate of authenticity.
Estimate: £600-800