Identical units are described on this site as having a 200 IG water tank and depicted with a single transverse mounted rear 180 foot 3/4 inch first aid hose reel.
This is indeed a hose reel tender but designated HrT/TV by NAFB as they originally all towed trailer pumps. The ones supplied to English brigades (Lincolnshire and others) had 200g tanks. The six supplied to NAFB had 150g tanks and also carried a LPP, usually a Coventry Climax FWP. JST314 is still preserved in Gloucester by myself.
Added by Rob Johnson on 21 September 2022.