Siddeley Special 30HP Sports Tourer

Concorso d'Eleganza Villa d'Este 2021

Coachwork by Vanden Plas, London

Year 1933 Chassis N° 3300 Body N° 3076


Reihensechszylinder aus der Aluminium-Legierung Hiduminium, Hubraum: 4960ccm Leistung: 91kW 


Einziger und letzter originaler Siddeley Vanden Plas Open Tourer Weltweit!


Born out of the 1919 merger of Armstrong-Whitworth's car division with the Coventry-based Siddeley-Deasy, Armstrong-Siddeley was more noted for its automobiles' high quality of construction, rather than their outright speed. Nevertheless, the firm did produce one outstanding high-performance model in the 1930s - the 30hp Siddeley Special, which debuted in chassis form at the 1932 Motor Show at Olympia. The following year a Vanden Plas-bodied tourer took one of the concours prizes at the RAC Rally, and by the time manufacture ceased in January 1937 no fewer than 17 different coachbuilders had conceived bodies in a wide variety of styles for the 253 chassis produced, of which no more than 20 survivors are known to the Armstrong-Siddeley Owners Club.

Crafted in hiduminium alloy - a spin-off from the firm's aeronautical activities - the Special's magnificent six-cylinder overhead-valve engine produced 125bhp at 3,200rpm. A seven-bearing design displacing 5.0 litres, this paragon of power units transmitted its abundance of low-speed torque via a Wilson pre-selector gearbox, and could propel the heavyweight Special smoothly from walking pace to over 90mph in top gear.

The Special's blend of engineering excellence and a performance to match Bentley's 'Silent Sportscar' guaranteed its appeal, though the high price meant that ownership was necessarily restricted to a wealthy elite, Sir Malcolm Campbell and Tommy Sopwith among them. Nevertheless, its blend of performance and quality must have been of some concern to Rolls-Royce.


Chassis 3300 was made on October 27, 1933, Vanden Plas created this beautiful open tourer coachwork (design 1003), and fitted it to the car on December 10, 1933.

The car was delivered by the agent Warwick Wright on January 12, 1934 to the Marquis of Huntley in a black livery and ocre leather upholstery. In total, 4 open tourers where build, but only one to design 1003.

Today, this highly original car in splendid condition is the only original Siddeley Vanden Plas Open Tourer in existence worldwide!

Siddeley Special Six


At this period Armstrong Siddeley cars, unlike certain other illustrious makes, made frequent and successful onslaughts on competitive rallies. Many prizes were won in the 1932 R.A.C. Rally, the make was represented in the Monte Carlo Rally and in 1933 three exciting new Siddeley Specials competed in the R.A.C. Rally, each car carrying four passengers so as to gain extra marks. The new Siddeley Specials were in the hands of C. D. Siddeley, Humphrey Symons and S. C. H. Davis.

This new 30-h.p. Siddeley Special was a very sensational new car, which had appeared in chassis form at the 1932 Motor Show. 


It retained the engine dimensions—88.9 by 133.4 mm. (4,960 c.c.)— which the 30-h.p. Armstrong Siddeley had used ever since 1919, so probably the same crankshaft and connecting-rods, etc., were retained. But crankcase, cylinder block, sump and cylinder head were made of separate castings of Hiduminium light alloy, as were the pistons and connecting-rods. Wet cylinder liners were used, sealed by a copper and asbestos joint at the top and by a copper diaphragm, retained by two castellated ring nuts on liner and cylinder block sleeve, these being tightened by means of a special spanner. 

About the only ferrous metal parts in this remarkable light-alloy power unit were the crankshaft, which was fully counterbalanced, ran in seven bearings and carried a friction-pattern vibration damper at the front, the camshaft and the valve gear, which incorporated Fabroil timing gears.

The stainless-steel overhead valves. push-rod-operated, seated upon aluminium-bronze inserts which were screwed, shrunk and then expanded into the cylinder head. The camshaft was driven from the front of the crankshaft and ran in four phosphor-bronze hearings. From it were driven the oil and petrol pumps. 

The ignition distributor was mounted vertically on the off side of the timing case, with the coil clipped to the cylinder block, and a long shaft with small universal couplings extended from the gear-driven dynamo to drive the water pump. 

Also, on the off side of this externally neat power unit were the sparking plugs, oil filler and float-style oil-level indicator. 

The near side of this fine engine was occupied by the manifolding, for a single downdraught Clandel-Hobson carburetter with hot-spotted manifold and two-piece exhaust system. 

The engine was inclined, so that a single universal-joint was permissible in the long shaft uniting the flywheel with a self-change four-speed gearbox mounted well behind the centre of the chassis. 

This preselector gearbox had no clutch, the gear bands acting as such. The channel-section chassis frame was double-dropped. amply cross-braced. and sprung on out-rigged ½-elliptic springs. 

Final drive to the spiral-bevel back axle was by torque tube enclosed shaft, there was worm-and-nut steering with the column adjustable for rake, and the cable-operated Bendix brakes were vacuum-servo-operated. 


The wheelbase measured 11 ft. 0in., the track 4 ft. 8 in., and the tourer weighed 38 cwt. Pulling a 3.6-to-1 top gear this Siddeley Special, in two S.U. carburetter form (twin S.U.s were adopted for the production cars), could go from 6 to 93 m.p.h. in top gear, attain 70 m.p.h. in third gear and reach 60 m.p.h. front a standstill in 18½ seconds. 


357.000 € (Brutto inkl. 19% MwSt./VAT)


300.000 € (Netto, Export Price)







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