Watch List notes:

(g) Elizabeth II (1952-), Proof Half-Sovereign, 1989, '500th Anniversary of the Sovereign', by Sindall, Queen seated in King Edward's chair, rev. Tudor Rose, edge milled, 3.98g, 12h (Marsh 544H; Spink SB3), brilliant uncirculated.
NGC PF70 ULTRA CAMEO (Certification #5880286-011)
, https://www.ngccoin.com/certlookup/5880286-011/70/
Estimate: £250 - £350