Hi Andy SCCC
As stated by others I have the Prowler 15hp which has a Kohler engine. I bought it 2nd hand 5 weeks ago with 22 hours on it, so its virtually new. Works very well, is lighter then a "conventional" TM basically because it has no waste tank. Its on wheels but not so portable. Can be got in out of van but you would need ramps (dont cost a lot - I have a set for my Cimex). The 15hp has a bigger blower and bigger pump the the 13hp.
The smaller red one is 13hp with a Honda engine. I have used one briefly, impressed with that as well. This one has more then enough grunt to clean big houses and with spare capacity.
John Kelly imports these, along with a newly introduced 20hp, which is more conventional in as much it has a waste tank.
Prices - depends on how the £ - $ thingy is. You need to talk to JK at Restormate - link on another post.
I would recommend - but check the pricing .