Here are the arms recorded in 1970, following the Post Office Act of 1969:
(vol 50 folio110): Gules, billetty bendwise Argent a barrulet wavy Or.
Crest: a phoenix proper holding in the beak a caduceus Or.
Supporters: upon a compartment of grass Vert bisected palewise by water barry wavy Argent and Azure are set for supporters on either side a pegasus Or crowned with an ancient crown and gorged with a collar Gules charged with a barrulet wavy Or.
The revised arms were created as the British Telecommunications Act of 1981 removed telecommunications from the functions of the Post Office so the barrulets, symbolic of buzzing wires, could be removed. Reference was also sought in the arms to the National Girobank, an important function of the Post Office, hence the arrival of the bezants:
1981 (vol 62 folio 59)
Gules, billetty bendwise Argent and in fess four bezants
Crest: a lion sejant grasping in its dexter forepaw a caduceus in pale, Gold.
Supporters: upon a compartment of grass Vert bisected palewise by water barry wavy Argent and Azure are set for supporters on either side a pegasus Or crowned with an ancient crown and gorged with a collar Gules charged of four bezants.
Incidentally, the caduceus is often mistakenly thought to represent medicine (which should use the single-snaked Rod of Asclepius) but is in fact a symbol of Hermes - of messages.
A few years later, the Post Office, probably Henry again, petitioned for a more everyday Ensign:
