Images of appointment books for the British Postal Service from 1737-1969 have recently been made available online.
You can find the records at Ancestry.co.uk, which says:
“These British Post Office appointment books are indexes to the Postmaster General’s minute books. They show the point when a person began working for the Post Office or started at a new position within the Post Office. The books were kept from 1831 until 1969, when they stopped being kept because of legislation and human resource procedures.
“Some records contain the job the worker was appointed to and the British Postal Museum’s website has the abbreviations in their Family History Guide.
“The index contains:
- Date of appointment