This is a 1910 Tower of London, On His Majesty’s Service (O.H.M.S) envelope, sent to Stowmarket, Suffolk. The Tower cachet is at the top right in violet ink, alongside the OFFICIAL PAID circular date stamp, in red, dated 13.JU.10. The arrival date stamp on the reverse is also the 13th.
This charming cachet was originally designed at the Tower and produced at His Majesty’s Stationery Office (H.M.S.O). This was the earliest design and was applied in the Constables Office. It was in use until 1912 when it was replaced. An interesting item which can be found here.