The railmotor was based on largely standard mechanical parts with a water-cooled Baguley engine which had four cylinders, each with a bore of 4" and stroke of 5". It was capable of developing 25 hp, having a three-speed gear with the final drive by inverted tooth chain to one of the axles. Reverse gear gave all three speeds and there were controls at each end, although the brake and gear levers had to be removed from the cups into which they fitted. The four wheels were 2' in diameter and were of chilled iron, as opposed to the normal steel, by British Griffin. The wheelbase was a little longer than customary at 108 inches, the weight only six tons and the maximum speed about 25 mph on the level. The petrol consumption was stated by the makers to be 16 mpg 'on easy grades', which worked out at a running cost of about 6d per train mile.

The body was an enclosed (unusual till then) ‘tramcar’, which was 19' long and 8' wide; was of three-ply wood panelling covered with thin steel sheeting; and the windows were of the 'drop' variety. There was a centre gangway with wooden-slat seats on either side which gave accommodation for thirty persons, and there was room for another twelve standing. Lighting was by acetylene but electric lights seem to have been provided by 1927. Doors were on either side at each end, with steps to give access from track level. The roof, which was only 8' 3" from rail level (making it much lower than a normal railway carriage), was railed around so that luggage could be carried on it; access was by a ladder at each end, a virtually unused feature it shared with Stephens later railmotors. The vehicle had the normal Drewry inside suspension but, unusually, full standard gauge pattern buffing and draw gear which emphasised the low height of such cars. Originally the petrol tank was inside the car body, but for safety reasons was later replaced by a horizontal cylinder above one buffer-beam. The exhaust-pipe rose to above roof-level and there was a whistle hinged to it and held at an angle by means of a spring. This was operated by pulling a wire inside the car which effectively joined the whistle to the end of the exhaust-pipe.

The railmotor was painted in what was the probable standard Drewry livery of dark green with yellow lining and on delivery had the company's title in a smart garter on the sides. In the 1930s this was replaced by the initials 'WC & PR'.

Small railmotor with trailer

A very similar car was later supplied by Drewry in 1927 to the Eten Railway in distant Peru.

Limited seating for other than the quietest days was soon apparent and to give the railmotor more versatility extra capacity was needed.  A photograph shows 1252 coupled to the former Metropolitan Railway four- wheeled coach, number 7 that the WC&P used as a spare for its usual fixed sets. This was a not a practical arrangement and it is highly unlikely that it was used in public service for the Drewry, which was too light to have braked the heavier coach (c10 tons) as it did not have continuous brakes.

A purpose built ‘tramcar’ trailer was therefore ordered from Drewry in November 1922 and delivered in March 1923 and the two worked happily together without continuous brakes. Described by its builders as  ‘enclosed’ it  was in fact of a semi enclosed type with open sides protected by  waterproof curtains and seated 24, a figure which seems often to have been exceeded at peak times. Curtains proving inadequate, the opening side were filled and side windows provided sometime after 1929. Like the railmotor, the trailer was painted green with yellow lettering, but by the closure was in plain dark green. After withdrawal the body is reported to have become a summerhouse in a garden at Chiseldon, near Swindon.

Later it became apparent that the addition of a goods trailer would enable the railmotor to handle the extensive milk churn traffic. A small wagon, No19, an ex MR three-plank drop-side wagon, was adapted for use with the railmotor.

However like the earlier coach the wagon proved too heavy for the limited haulage and braking power available and a special wagon was ordered from Cranes of Dereham to run with the railmotor instead. This was delivered on 21st September 1925. It had a capacity of 3 tons 10 cwt and was fitted with a three-plank body measuring 12 ft x 7 ft with sides 18 inches high. Screw couplings and side-buffers of normal height were fitted.

The railmotor with its trailers was so successful that by 1927 its mileage exceeded that of all the steam locomotives put together; which were now only needed at peak periods and for goods traffic. The summer timetable now only required the railmotor and one steam engine, the latter being used on the trains which ran through to Portishead and were therefore normally mixed because of the quarry traffic. For the same reason it was necessary to use one steam engine in winter.

Neither this nor the later railmotor were without hazards .The large railmotor was prone to slipping when the brakes were applied, particularly under wet conditions, and it was on such a day that the 3.55 from Clevedon to Weston, a train regularly filled with home going schoolchildren. On approaching Worle the car was travelling too fast to pull up. The brakes were applied but they failed to grip, and the railmotor sailed into the first crossing gate. This turned out to be not properly secured and it swung across the road, which fortunately was clear at that moment! Another drawback of the railmotors, a complaint common to contemporary road vehicles, was the propensity of the radiators to boil over. Indeed, under very hot conditions it was not unknown for the radiator to need refilling at every station, although leakage no doubt played its part, a problem also dealt with in traditional form: a handy patch of cow dung mixed with water added to the system soon did the trick.

The Large Drewry

Meanwhile elsewhere the Southern Railway was seeking economical solutions to providing services on some of its minor branch lines. As a result, in April 1927 the General Manager instigated a review of operating these services by steam or petrol-engine railmotors. To test the latter a Drewry railmotor was ordered. There is considerable variation in reported dates of order and delivery. The Drewry Board minutes record that it had been ordered in March 1927 but Bradley (probably based on Southern records) gives June 1927. Whatever the original order date, R E L Maunsell took a personal interest in the deliberations and specifications, even over quite minor matters, seem to have changed over the months. It took till August 1927 for the Southern to harden its requirement to a four wheeled car to seat 25 and to include a guard's compartment to carry milk churns. It is an interesting speculation whether Stephens, who was friendly with both Maunsell and his General Manager, was informally consulted for his experiences during these deliberations.

The order was finally placed on 13 December 1927 for what the Southern designated a 'branch line car'. A four wheeled car with full railway buffing and drawgear, it was to carry 25 third class passengers and had a separate compartment for 28 milk churns. With a body length of 31ft and a wheelbase of 20 ft the body was far nearer normal railway practice than the earlier car, for Drewry had by then adopted a more conventional approach and suspension, radiator type and body reflected this. It was rather large for its 50hp engine, which gave a great deal of trouble in service, particularly due to vibration. Transmission was through a three-speed gearbox, and there was an electric headlight at each end, a direct reflection of the alteration made in 1927 to the WC&P motor. Delivered on 21 May 1928 it had a seating capacity of 26 and weighed 10 tons 17 cwt.