By Rod Ward
The existence of the Sentinel marque is thanks largely to two men, both called Stephen Alley, father and son. Stephen senior went into a partnership as Alley & McLennan in Glasgow in 1875. This engineering company was very advanced for its time, producing prefabricated ships and even prefabricated buildings, including its own factories, all under the Sentinel trade name. Stephen Alley died in 1898 and his 26-year old son took the helm, diversifying into steam-powered vehicles by taking over a Manchester firm called Simpson & Bibby. During the Great War steam waggon production moved to Shrewsbury, in a new company separate from the Glasgow engineering concern. During a period when many steam vehicle manufacturers fell by the wayside, Sentinel and Foden were the two biggest firms left in the business, Sentinel with its advanced ‘undertype’ engine layout. It could not last; even a licence for the advanced Doble steam patents led nowhere, and Sentinel had to consider motor vehicle manufacture. In 1933, therefore, Sentinel took over Garner Motors. Sentinel fell into receivership in 1936, however, and Garner had to be sold. Sentinel still produced railway locomotives, and the firm also dabbled in producer gas plants by taking over HSG, which had taken over the old Gilford factory in London. By this time the Second World War had broken out, and Sentinel were fully employed on war work. When peace returned the railway locomotives were revived, and a new range of Sentinel diesel-engined lorries and buses was launched. Sentinel employed advanced techniques for the period; Ricardo-designed horizontal underfloor diesel engines and unitary bus body construction. These vehicles only lasted in production at Shrewsbury until 1956, however, though TVW extended production until 1960, when the component stock ran out. Rolls-Royce took over Sentinel, in order to build diesel engines in the Shrewsbury works, and they continued Sentinel railway locomotive production, in conjunction with THR. The last Sentinel-badged railway locomotive was produced in the early 1970s, almost a century after the brand first appeared.