Complex sentence: The photograph was thought to represent a typical Australian Aboriginal man so was used on an 8½ pence stamp and a 2 shillings and 6 pence (half crown) stamp in 1950.
Split into simpler sentences: The photograph was thought to represent a typical Australian Aboriginal man. The portrait was then used om an 8½ pence stamp and a 2 shillings and 6 pence (half crown) stamp in 1950.