Museum volunteer Corinne Codd with local postman Kevin Wilcox.
Victorian innovation is being celebrated in a set of stamps dedicated to the humble letterbox postbox.
The idea took hold with slots being installed outside post offices rather than the more substantial version such as the freestanding postbox in Haverfordwest Town Museum.
Dating from 1857, it's the oldest survivor of its kind in Wales.
It was rediscovered in a garden off Merlin's Hill, where it was being used as a gatepost.
Museum curator, Simon Hancock, said: "The postbox was found in someone's garden rusting away.
"When the significance of its history was realised, it was sent off to Royal Mail, who restored it to its former glory."
"It was then given on loan to the museum in 1991, where it has remained ever since. We are delighted that the postbox is being celebrated once again by Royal Mail on a set of stamps."
Some of the stamps showing the letterbox slots all over Britain
Britain's first roadside pillar boxes arrived in 1852 in the Channel Islands and in 1853 on the mainland.
From 1857, they began appearing in walls, buildings or brick pillars and were later to be found on poles and lamp posts.
A cheaper and more practical alternative was needed for less populated or remote areas - and the smaller postbox was developed.
The colour changed from green to blue to the familiar postbox red.
The miniature sheet issued features four wall mounted boxes.
Production of wall boxes ended in 1980, and in 1995 freestanding pedestal boxes were introduced, but around 114,000 post boxes of all kinds still exist across the UK.
There are 9,000 postboxes in Wales, some dating back 150 years.
The earliest known surviving posting slot was placed in the wall of Wakefield Post Office in Yorkshire in 1809, and like many others, was installed for the convenience of people posting unpaid letters (the letters were paid for by the recipient).
Val Bodden, Royal Mail External Relations Manager, said: "We are lucky to have one of the oldest posboxes here in Wales with some fine examples of Victorian boxes dotted across Wales."