Express Rates 1892-1980
1921 - 5½d third step overseas postage for 2-3oz + 3d express fee
a couple of months before the first rate increase
Overseas express post was introduced the year after the inland service, and allowed the sender to prepay the foreign fee for express delivery at the destination according to the local regulations.
It was not available to all countries, or necessarily to all places in countries that did offer it, and only covered basic express delivery – which usually meant in the vicinity of the office of delivery. So it was still possible for an addressee to be charged extra if they were outside this boundary. The fees were usually (but not always) the same as the inland fees.
Express Delivery was replaced by the Swiftair service in 1980. (That service was only available with airmail or all-up mail, although there had been little point in using the express service with surface mail for some time.)