A really interesting website:

http://locoperformance.tripod.com/edition07/eusbham.htm

with several recordings of timings from New Street to Euston behind Bushbury Jubilees. Some of the 14 coach trains had a Black 5 pilot (note to self, that could be a useful addition to the roster!). Speeds in the mid 80s were not uncommon on these runs.

I particularly like the following comment:

"But the Bushbury Jubilees were no ordinary Jubilees: they were the elite. When I got to know them from 1955 onwards the allocation comprised 45647, 45688, 45703, 45709, 45733, 45734, 45737, 45738, 45741, and 45742. They were kept in immaculate condition, and performed accordingly (Well, mostly!)."

Note that Polyphemus was one of them.