Brush type 4 Class 47

Another of Mr. Hill's B/W shots. At at a time when the parlance for these machines was the 'Brush Type 4' this Class 47 waited at Reading.
There was a chap next to me at Eurotrack running one of these in this livery and I kept wondering whether I could justify one on Rhiw....err no.
After raking around for headcode clarification for Unnycoombe two days ago, the answer stares you in the face.