After doing some digging, I found that this is a Fowler 16263 'Talisman' belonging to the Pickfords removal company delivering an M.G. cylinder to St. Anne's Board Mills in Bristol in 1938.
Corgi apparently even made a toy of this event.
Apparently the M. G. stands for "machine glazed" and refers to making shiny paper.
I would have assumed it was a giant electric motor, so thanks for the link.
I just wish there were diagrams to show the interior and mode of operation.