While I was browsing around eBay UK, I found a lot of forty library 78s on there, which mostly consists of 78s from Southern and Chappell, and while I was looking at the images for this lot, I found this:
This is a 78 from Southern numbered MQ 962. This is an extremely noteworthy find, because we thought the 78 catalog stopped at MQ
961. This 78 features a cue that would later show up on MQ/LP 36, named "Thunder Hole" by George Cole, though we don't know what the other track or tracks are on this 78. There's a possibility that the other cues on MQ/LP 36 could be from 78s as well, but we don't know if those 78s are confirmed to exist.