Spotted

This was spotted at the Naval Museum recently.  Does anyone have an answer?

What is unusual is his Branch Badge.  Ian (Manga) Heperi (RIP) was a Signalman, but is wearing a Radioman badge.  Could this be the period when RO(G)s and RO(T)s wore the same badge.  If not, then it raises the question of what was he doing in a Sparker’s shirt?