Edward VI, second period, Shilling, Tower II mint, 1550, m.m. martlet/crowned leopard's head (Bispham bust 5; N.1919/1; S.2466), good fine, an extremely rare mule of marks

The mintmark crowned leopard's head is so rare that it was not correctly identified until a clear example turned up in 1979, c.f. BNJ 1980, p.135. Only two coins with the leopard's head mark on both sides and two martlet/leopard's head mules were known at that time.