The DP 1 was designed primarily as a water transfer vehicle to keep major foam vehicles supplied at aircraft crash fires.  With a built-in foam tank and round-the-pump proportioner system it was also capable of producing foam through sidelines and was often equipped as domestic vehicle on airfields.  Some variants were also fitted with screens and monitors for dealing with special risks such as Bloodhound Missile sites.

Chassis
 

Thorneycroft Nubian 4 X 4

Engine
 

Rolls Royce B81 Petrol

Water Tank Capacity
 

700 Gallons

Foam Liquid Tank Capacity

35 Gallons

With a bigger water tank and monitor, the DP 2 was a larger and more effective version of the DP 1 .  It's only drawback was it's very limited locker space.

Chassis
 

Thorneycroft Nubian TFA 6 X 6

Engine
 

Rolls Royce B81 Petrol

Water Tank Capacity
 

1000 Gallons

Foam Liquid Tank Capacity

50 Gallons

Although the DP 3 was primarily for rapid transfer of water to major foam vehicles it was in many ways a fore-runner to the Mk 9, having a large monitor capable of throwing aspirated foam over a long distance(170 ft). With hydraulically operated valves it was considerable more “high tech” than earlier DPs.

Chassis
 

Thorneycroft Nubian TFA 6 X 6

Engine
 

Rolls Royce B81 Petrol

Water Tank Capacity
 

954 Gallons

Foam Liquid Tank Capacity

55 Gallons