Construction of this strange flying test rig took some year and a half and was completed in February 1958. The following three months saw the normal static and systems test being carried out until the first engine runs commenced on 3rd June 1958. During the following dozen days the rig undertook 20 hours of dynamic system testing and tied down engine running. These trials were obligatory prior to the first flight. The prototype was registered G-APLE on 27th February 1959.
15th June 1958 saw the maiden flight of the prototype piloted by Lieutant W H 'Slim' Sear at Yeovil, Somerset. Flight trials continued throughout the summer of that year but a large amount of vibration was being experienced which was proving difficult to cure. Therefore, a number of changes were made to the design of the second aircraft, known internally at Yeovil as WG.7. These changes included the use of different sized tubes and gauges in the fuselage construction plus a six-blade main-rotor from the Sikorsky S-64. With the mandatory ten hours minimum flying hours achieved, the first Westminster, was readied for an appearance at the SBAC Show at Farnborough between the 1st and 7th September 1958. At the show the large helicopter caused quite a stir and was described as 'a flying cutaway drawing'. Incidently, the end of the demonstration of Westland machines was marked by the helicopters arranging themselves in a line before the Presidents area and neatly bowing, a precedent that is carried out today by the Harrier family. By this time, Westland's had sank nearly £1.5 million of their own money into the private venture project.
The second example was registered G-APTX on 5th May 1959. At the time of the completion of the WG.7 design, there were rumours of the Admiralty having grave concerns about the Westminster project interfering with the Wessex development program. Pressure was beginning to be felt to encourage the company to pause the heavy-lift project until the Wessex programme was completed. In reality, the Westminster project had no effect on the Wessex introduction, indeed the prototype Wessex flew some five months ahead of schedule. However, the writing was on the wall for the project. As Westland's prime client the Admiralty carried a great deal of influence and the firm realised that the writing was on the wall for the heavy-lift project.
However, work on the two existing helicopters continued. G-APLE's space frame structure was given a streamlined shape with the addition of plywood frames and wooden stringers covered with Terylene fabric. Terylene was a generic name for a synthetic thread, which had the advantage of nylon, but did not have the undesirable high degree of elasticity. Because of its lower elasticity, it did not present the problem of thread retraction after cutting. As with nylon thread, it was highly resistant to moisture and retained a large part of its dry strength when wet. Terylene was also almost entirely free from contaminating metals which might tend to cause degradation. The material applied to G-APLE had a special coating applied to protect it from gearbox and transmission lubricating oil. The machine first flew in its new covering on 17th June 1960.
Between the 7th and 13th September 1959, both Westminster examples were on show at the 20th SBAC Show at Farnborough. The machines were demonstrated alongside the Wessex, Whirlwind and Widgeon. G-APTX appeared with more skinning visible and sported large external tanks. G-APLE demonstrated a 3,500 lb (1,587.6 kg) bridge span which was carried to a prepared site on the airfield and lowered slowly onto two ramps. Once this was done the Wessex with a Land Rover and gun combination underslung, and a Whirlwind lifting an Austin Mini-moke landed their cargoes and proceeded to cross the newly completed bridge.
In 1959 extensive weight lifting trials were undertaken with a variety of loads. The company made a great deal of the fact that it was the Westminster was the largest twin-turbine mechanically driven single-rotor helicopter in the Western world, at the time. Its ability to be able to operate with a full payload on one Eland engine was also claimed in press release.
Westland stated in a press release concerning lifting techniques:
"The design of the crane-transporter version provides for the carriage of loads externally, although it is possible to dispose internally as well where shape and size permits. The fuselage structure could be modified to introduce rear-loading facilities should this be desirable for certain roles. However, investigations of the various methods of carrying loads have shown that for many transportation duties over distances up to 100 miles freight and equipment is best carried externally. The increased flexibility of unrestricted load sizes and shapes, and the rapidity of external loading and unloading, combined with the possibility of jettisoning the load in an emergency, are obvious advantages ... Moreover, by this method loads can be ferried into and out of locations where it is not convenient or possible for the helicopter to land. A single load anchorage point has therefore been built into the base of the fuselage structure for securing a sling mechanism, and a hoist is provided to wind in the excess cable length after the load has been attached ..."
The manufacturers believed that with a disposable load of 14,000 lb, the Westminster would meet military requirements for any large transport helicopter and would be able to carry heavy field equipment, tactical and nuclear weapon loads and armed troops over stages of 150 miles or more. A typical Westminster military trooping assignment was the carriage of 51 troops, five missiles or four jeeps.
In 1960, a new six-blade main rotor was fitted to investigate some problems, which had been encountered with blade stall at certain speed. These changes raised the aircrafts maximum speed to 155 mph and reduced the in-flight vibration problems. The same year saw the type take its final bow at Farnborough on 6th to 11th September, when a Terylene covered G-APLE was demonstrated.
The second Westminster, WG.7, was registered G-APTX and was first flown by 'Slim' Sear on 4th September 1959 at Yeovil. The first stages of the test programme proceeded smoothly but were against a period of severe uncertainty regarding the British aviation industry as a whole. At the same time the company were in the process of acquiring the facilities and rotary interests of the Isle of Wight based Saunders-Roe Company. Other acquisitions being made were for the helicopter interests of Fairey and Bristol. All of these changes resulted in a great upheaval for Westland with the reorganisation and rationalisation of resources and products. Many embryo projects as well as work on a number of prototypes were abandoned.
G-APTX was fitted with an external 250 Imperial gallon (1,135 litre) fuel tank and dual flying controls.
The Westminster project was under the microscope and its commercial value under scrutiny. It was categorised alongside the Bristol B.194 project and the Fairey Rotodyne. The Royal Navy's urgent requirement for the anti-submarine warfare variant of the Wessex was a major nail in the Westminster coffin. Another was that the Westland organisation could not proceed with all of the present programmes from its own stables as well as those newly acquired companies. Without any official Government support the project was doomed even though a budget of £400,000 would see the programme though the testing phase. The Fairey Rotodyne was at a more advanced stage of development and showed greater potential, therefore, in September 1960 the project work was abandoned.
The end of the project saw all of the Sikorsky supplied equipment such as rotors, drive heads and gearboxes, removed from the two Westminster's and returned to America. This avoided payment of duty to HM Customs and Excise. The two airframes were then dismantled and cut up and sold to the scrap metal merchant Coley during the winter of 1960-61. The first example was cancelled with the authorities on 29th September 1960. Some remains of the aircraft were believed to have been dumped at Yeovilton. The second example, G-APTX was officially declared withdrawn from use at Yeovil in September 1962 and scrapped. Precious little documentation is believe to have survived from the project.
So ended the short life of an adventurous attempt to produce a large private-venture British helicopter.