A classic image of the Queen which has featured on some 200 billion stamps is being celebrated in an exhibition.
Arnold Machin created the design in 1967
The British Postal Museum and Archive (BPMA) show opens at the Royal College of Art in London on Thursday.
Arnold Machin's headshot of Queen Elizabeth II marks its 40th anniversary this year and is thought to be the most produced stamp portrait of all time.
The exhibition traces the development of the design from its inspiration in the Victorian Penny Black.
The Timeless & Classic: Elizabeth, Queen & Icon exhibition, which runs until 15 August, includes original portrait photography and plaster casts.
Douglas Muir, curator at the BPMA, said: "This is a marvellous and unique opportunity to see the Machin design process in its entirety from the development of the coin effigy through the many stages of different designs to the final, timeless icon."
The exhibition also includes radical stamp designs, some without the Queen's head on them, which were instigated by the postmaster general Tony Benn in the mid-1960s.
The stamps not featuring the Queen were never issued.
Mr Machin's image was chosen from five artists asked to submit renderings of the Queen's head for a new stamp design.
It first appeared on a 4d value stamp issued in June 1967.