Both factory buildings were prefabricated in Glasgow for local assembly and in both cases core Scottish employees transferred to the new sites.

The company Sentinel Waggon Works Ltd was formed when steam wagon production was switched to a new factory, opened at Shrewsbury in 1915.

There were several other slight changes to the name over the company's lifetime when further infusions of working capital were required to obviate financial problems.

Alley & MacLellan's early steam wagon was so successful that it remained in production with relatively few updates until the launch of Sentinel's famous Super in 1923.

In 1934, Sentinel launched a new and advanced steamer – the S type which had a single-acting four-cylinder underfloor engine with longitudinal crankshaft and an overhead worm-drive axle.

In spite of its sophisticated design, however, it could not compete with contemporary diesel trucks for all-round convenience and payload capacity, and was phased out in the late 1930s.

It was not the end of Sentinel's involvement with steam, however; the company built about 100 "S" type vehicles for export to Argentina as late as 1950, for use by the Río Turbio coal mine.

In 1947 Sentinel offered to extend the agreement for diesel vehicles to include the steam locomotives and an agency was accepted by Thomas Hill for sales and servicing.

In 1963, Thomas Hill's decided to renew the loco agreement and relinquish the diesel vehicle agency, concentrating all efforts on the steam locomotive work.

Two of the newly developed steam receiver locos were delivered and proved very satisfactory in service, but Dorman Long did not approve.

The prototype Sentinel diesel locomotive was built and ready to commence trials on the former Shropshire and Montgomeryshire Railway (then under military control) early in 1959.

Between 1963 and 1966, a fleet of these diesel locomotives, eventually numbering five 0-6-0s and eighteen 0-4-0s, was supplied to the Manchester Ship Canal Company for use on the navigation's private railway network.

The rod-coupled Class 14 were powered by a 650 hp (480 kW) Paxman engine with Voith Transmission and were capable of doing the work required at a fraction of the price of new Steelman locomotives.

UK sales of Sentinel locos were now fewer than 10 per year, their only overseas success had been to license the assembly of 36 0-6-0 locomotives by Sorefame for the Portuguese Railways in 1965/66.

Based on a 200 hp (150 kW) 4-wheeled 0-4-0 frame fitted with two "gyro units" (see Flywheel energy storage) made by Maschinenfabrik Oerlikon of Switzerland.

The motor took its power from a side-mounted supply at static posts via a four-contact swinging arm extended or retracted pneumatically by the driver.

When the gyros had reached the required speed, the driver would retract the contact arm, switch the motor to generation and controlled the locomotive in a similar way to a diesel-electric loco.

Army 610 Three Sentinel steam locos were used at Amsted Maxion's railway equipment plant in Cruzeiro, SP (Brazil).

Now they are preserved at ABPF shops in Cruzeiro, near Amsted Maxion's plant:[28] Dapol has produced the Y1 and Y3 steam locomotive in various liveries including BR, LNER, LMS and NCB.