Watch List notes:

Nigeria, Elizabeth II (1952-1963), Double-Headed Mule Shilling, c. 1959-1962, by Cecil Thomas for the Royal Mint, London, crowned bust right, wearing Tudor Crown, rev. crowned bust right, wearing Tudor Crown, 23mm. diameter, incuse security edge with outer straight graining, 4.95g, 23mm. (cf. KM 5; Schön 36), two small rim nicks, otherwise lightly toned, extremely fine, an excessively rare and remarkable 20th Century mule.
NGC have elected not to certify this coin deeming it to be an 'Ineligible type' (Cert. #6295598-001). Spink is sufficiently satisfied as to the authenticity of this error to offer it for sale where it is sold under our publicised terms and conditions.
Estimate: £200 - £250