Half Sovereign 1818 having a 'spike' from the top right of the second 8, the IBNS article written by Graham Warboys (September 2020) indicates this as the key identifier for the Extremely Rare 8 over 7 variety. With only 9 examples believed to exist, one of the key types of the entire Half Sovereign series, Near Fine/Fine Ex-Jewellery
Estimate: GBP 250 - 500