I photographed this vehicle in Heaton Park, Manchester at the Trans Lancs Historic Vehicle Rally in September 1995.
The programme of the event describes it as follows:
Karrier 73 A WRT, 1955 WTE 893
Entered by L A Reid, Bacup
Used by Lancashire County Fire Brigade until 1968 and sold to ICI at Fleetwood
Acquired by present owner in 1986.
I've not been able to find out much about this vehicle, except that 'WRT' or 'WrT' seems to stand for 'water tender'. The Karrier Wikipedia entry infers that it's based on the Karrier Gamecock or Bantam.