Don’t doubt it mate, but what Dai describes is a 30, no ifs, no buts, it’s 30 and it was a 30 forty years ago too.
Be interesting, if someone had an interest in such things, to read the details and how they came up with 7
Edited to add:
Sounds like I’m calling Dai a bulshitter and I’m not, I don’t know because I don’t know, it’s just a strange one and Dai probably thinks the same.