Darlington CB had one of these, which was towed behind a Land Rover when the brigade had to attend rural calls.
The town's two pump water tenders did not carry portable pumps, so this went along in case open water access in a restricted space was likely to be needed. I believe the idea was that this pump was light enough to be dismounted from the trailer and carried to the water source if necessary, too.
On the other hand, it was a lot less useful than most of the portable pumps in those days, which could deliver up to 250 gpm - or even 350 if you borrowed the Green Goddess' "portable" unit!
Added by Paul Sturman on 17 September 2015.