The record
The Mark 4 closed out the turreted Armoured Patrol Car branch of the Shorland family, the line that runs from the RUC prototypes through the Mark 1, 2 and 3. It should not be confused with the enclosed SB.401 Armoured Personnel Vehicle, which is the personnel-carrying branch of the same generation: both received the V8, but only the Mark 4 kept the turret. Short Brothers of Belfast — the company had dropped the 'and Harland' from its name in 1977 — put the Mark 4 into production in 1980, and the figures Shorts supplied in 1990 give over 250 sold.
The change that defines the mark is the engine. Where the Mark 3 used the 2,625 cc six, the Mark 4 took the Rover 3.5-litre V8. The Shorland Site quotes its output as 91 bhp at 3,500 rpm, which is an unusually low figure for that engine and identical in horsepower to the Mark 3's six; no consulted source explains the discrepancy, and Wikipedia and Gun Mart record only the capacity. What is not in doubt is the packaging consequence: the bigger engine forced the radiator much further forward, so that on a Mark 4 the grille sits level with the front of the headlamps. Weight and dimensions were otherwise identical to the Mark 3 at 2,941 kg unladen.
Detail changes went with it. Extractor fans and dual fuel tanks, options on earlier marks, became standard. The door handles no longer protrude but are recessed beneath the profile of the armour. The sidelights grew into the larger 'bug eye' pattern with a metal rim and a multi-faceted plastic lens, a screw-in replacement for the glass FV-type units common to British military Land Rovers. Air-conditioning equipment could be mounted on the bonnet for hot-climate customers, and military-pattern bumpers were not always fitted. A photographed example carries the military registration 06 SP 54.
Sources consulted do not set out a Mark 4 operator list separately from Shorland totals, and the mark's chassis is not stated explicitly by the Shorland Site; the contemporary V8 Shorlands are generally understood to sit on the Stage 1 V8 long-wheelbase Series III platform, which Bob Morrison identifies explicitly as the basis of the parallel SB.401 APV. In the Netherlands the Rijkspolitie operated Mark 4s alongside its Mark 3s, with registrations recorded as BY-21-JR, VG-27-LR and BY-07-KV. The Mark 4 was superseded by the coil-sprung, Defender 110-based Series 5 family, and the complete Shorland design was sold to British Aerospace Australia in 1996.
