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The Rolls-Royce 20hp was conceived out of economic necessity after the Great War, but it went on to be developed into a range of more powerful Rolls-Royce and Bentley cars, culminating in the Silver Cloud I, 1955-1959.

Although the idea of a small car was discussed as early as 1918, work began in earnest in 1920 after much internal discussion and soul searching. Eventually the engine was decided upon: with six cylinders inline; a detachable cast iron head, a cast iron block; push rod operated overhead valves; and with the spark plugs on the opposite side of the engine to the push rods. The cylinder centres were 4.15” (105.4mm) apart, except for numbers 3 and 4 where they were 4.65” (118.1mm) apart. The stroke 4.5”, and importantly all these dimensions were held constant up to the end of Silver Cloud 1 production in 1959. The bore was set at 3” and the crankshaft had seven bearings.

After considerable road testing and development work, the new 20hp was launched at the London Motor Show in October 1922, and was described in The Autocar of 6 October 1922. Between then and when production switched to the 20/25 in 1929, 2,903 (plus 10 experimental) cars were produced at Derby. During that time there was continuous development of the chassis, major improvements being:

  • Stand-by magneto fitted 1923
  • Handbrake lever moved to driver’s side 1924
  • 4-wheel brakes fitted, with mechanical servo 1925
  • 4-speed gear box fitted with gear lever moved to driver’s side 1925
  • Well-base wheels fitted 1926
  • Oval web crankshaft 1928
  • Vertical radiator shutters 1929
  • Part central lubrication 1929

The 20hp Register was the first register to be formed within the RREC in 1994. Eric Barass (late Chairman of the RREC) wrote: “The 20 Register is unique in that it caters for the only truly vintage model in the Club, and has always attracted lovers of Sir Henry’s own special favourite.” Keith Jay was Register Secretary, and Ben Grew, John McGlynn and Graham Pearce were Regional Representatives. Andrew Sington was Editor of the 20hp Newsletter. Rallys to Europe were organised, the first by the 20hp Register to Brittany in May 1995.


History of the RREC Registers

The first single-model Registers were set up by the RREC during the period 1992 to 1994.  It is worthwhile to relate the history, as revealed in contemporary Bulletins.   During the 1980s the RREC expanded rapidly as many owners of modern Rolls-Royce cars joined the Club.  Naturally, more and more rallies and tours were arranged with these new faster cars in mind, but there arose a feeling that owners of older cars were finding it difficult to participate in these events, which tended to involve high daily mileages.

The possibility of setting up single-model Registers within the Club was discussed, but there were misgivings in case this would create divisions and cliques.  On the other hand there was a danger that rival Rolls-Royce car clubs, aimed at pre-1960 models, could be set up.

The RREC arranged its first two single-model events in 1992 and 1993.  These were so successful that the first Register (20hp) was formed in 1994, closely followed by others, as described below.

In Bulletin 189 (Nov/Dec 1991) a weekend rally was announced for June 1992 at Blenheim Palace to commemorate 70 years of the 20hp.  The organisation was masterminded by Keith Jay with help from several members of the Oxford Section.  It was hugely successful: eighty one 20hps attended, along with about 100 other Club cars.  Brian Bilton-Sanderson (General Secretary) wrote: “it was something we should have done years ago!”  As a result it was stated that the model register idea had been tested, and that Registers would be formed (B193 and B194).  Another weekend event to celebrate 50 years of the Derby Bentley was organised jointly by the RREC and the BDC at Bosworth Hall in June 1993, reported in B199 (July/August 1993). 

However there was still some determined opposition, and only after debates at both 1993 and 1994 Club Conferences was the formation of the 20hp Register eventually announced (B204, May/June 1994).  Keith Jay was Register Secretary, and Ben Grew, John McGlynn and Graham Pearce were Regional Representatives.  Andrew Sington was Editor of the 20hp Newsletter.  The first issue was published in September 1994 with contributions from Keith Jay, John Fasal, Ben Grew, Eric Barrass and Andrew Sington.  Eric Barass wrote: “The 20 Register is unique in that it caters for the only truly vintage model* in the Club, and has always attracted lovers of Sir Henry’s own special favourite.”

New Registers were quickly launched.  Owners of earlier cars were “emerging for the first time in many years at the thought of events based on compatibility” (B205).  Eric Barrass wrote an article explaining the “Philosophy and Concept of Registers” (B209).  Rallies to Europe were organised, the first by the 20hp Register to Brittany in May 1995.  Silver Ghost and Shadow events were announced for September 1995 (B211), and a 25/30/Wraith rally to Brittany was announced for September 1996 (B212).  Registers were on the move!

* The Vintage Sports Car Club Ltd of the UK defines vintage cars as those built between 1 January 1920 and 31 December 1931.  Eric was referring to the fact that the 20hp is the only Rolls-Royce model which is entirely “vintage”.  Some countries define vintage cars differently.


The 20hp Register Today

The aim of the 20hp Register is to provide a forum to help 20hp owners throughout the world make the most of their vintage car. The services of the 20hp Register are in addition to and complimentary to those provided by “corporate” RREC and the Area Sections.

The Register is for members and non-members of the Rolls Royce Enthusiasts Club and endorses the goals and aims of the Club.  A member does not have to own a 20hp to be on the Register.

Registered members are given priority invitations to events.

The Register fully supports the technical seminars run at The Hunt House and encourages members to attend.

The Register organises an interesting touring programme and an annual 20hp event where members and their families can enjoy being with other 20hp owners; can exchange experiences, problems and solutions; and can have their cars appraised.

The 20hp model is popular with vintage car enthusiasts whether they want it for their museum collection, occasional local driving or extensive touring.  A 'sorted' 20hp is highly reliable, yet relatively simple, so it is possible for the average do-it-yourself mechanic to maintain it in a reliable state.  Compared with the Silver Ghost or Derby Phantoms it has reasonably good fuel economy, typically delivering 18-22 mpg.  Even better performance is achieved by fitting a modern overdrive unit.  All this explains why the 20hp is one of the most popular marques used for vintage touring.

To join the Register see 'Contact us'.



Source and artist unknown.  Early 20hp chassis




Adapted from a drawing by an unknown artist in The Autocar 13 October 1921.

Very early car, note handbrake in central position.  (Moved to driver's side January 1924)



Adapted from a drawing by Max Millar in The Autocar 2 October 1931.

This third chassis drawing is of a very early 20/25 which is more or less the same as the late 20hp. Visual differences include a cast dash, headlamp pillars, double spare wheel support and round Autovac which replaced the square Autovac during the GVO series in early 1929.