Free franked wrapper from ‘Sussex’ aka the Duke of Sussex aka Augustus Frederick son of King George III, sent in 1828 to his private physician Dr Pettigrew who also had a side hustle as a renowned Egyptologist - an interest he happened to share with his patient. His nickname was ‘Mummy Pettigrew’ as he was known for unwrapping mummies in his lectures. So they were either likely corresponding about mummies or gout… ‘official business’ - I think not!

The address is on Saville Row, now famed for its bespoke tailors; back then it was just a residential street for posh folk in heart of Mayfair.

Fred - being to the manor born - lived at Kensington Palace. but one of his many titles was Sheriff of Nottingham! Hence the sending postmark…