| Description | Date | Identifier | |
| Order for letters and numbers to be placed with Messrs. Cornercroft Ltd. | 14th Oct 1937 | Box 148 \ 4 scan0250 | |
| Requesting one number plate to be cast for car RC.5930. | 2nd Feb 1938 | Box 148 \ 4 scan0251 | |
| Request to place an official order with Cornercroft Ltd. for number plate characters. | 2nd Feb 1938 | Box 148 \ 4 scan0252 | |
| Request to Cornercroft Ltd. for the characters RC.5930 for fitting into an interior number plate. | 2nd Feb 1938 | Box 148 \ 4 scan0253 | |
| Request to place an official order with Cornercroft Ltd. for characters for a rear interior number plate. | 23th Feb 1938 | Box 148 \ 4 scan0254 | |
| Request to have one front number plate cast for chassis RC.5642. | 23th Feb 1938 | Box 148 \ 4 scan0255 | |
| Request to Cornercroft Ltd. for characters for interior number plates. | 23th Feb 1938 | Box 148 \ 4 scan0256 | |
| Use of 'Duravistor' for rear number plates and condensation issues. | 19th Mar 1938 | Box 148 \ 4 scan0257 | |
| Request to obtain characters RC.6101 for the rear interior number plate of an experimental car chassis. | 21th Mar 1938 | Box 148 \ 4 scan0258 | |
| Cast front number plate for chassis RC.6101. | 21th Mar 1938 | Box 148 \ 4 scan0259 | |
| Request to obtain number plate characters 'RC.6137' from Messrs. Lucas for a Jaguar. | 26th Mar 1938 | Box 148 \ 4 scan0260 | |
| Request to have one front number plate cast for a Jaguar car. | 26th Mar 1938 | Box 148 \ 4 scan0261 | |
| Requesting registration characters from Messrs. Lucas & Co. for use on a rear interior number plate. | 15th Jun 1938 | Box 148 \ 4 scan0262 | |
| Requesting a front number plate be cast for car RC.6334. | 15th Jun 1938 | Box 148 \ 4 scan0263 | |
| Set of Homo number plates with specific shapes for RC.7211. | 27th Mar 1939 | Box 148 \ 4 scan0264 | |
| Suggestion for a built-in rear number plate as a solution to legal requirements. | 6th Apr 1939 | Box 148 \ 4 scan0265 | |
| Confirming a telephone conversation and subsequent order for two sets of pressed aluminium number plates. | 1st May 1939 | Box 148 \ 4 scan0266 | |
| Request to obtain a set of 'Homo' number plates with specific dimensions. | 9th May 1939 | Box 148 \ 4 scan0267 | |
| Confirming an order for 'Homo' number plates for vehicle RC.7420. | 23th May 1939 | Box 148 \ 4 scan0268 | |
| Confirming a telephone conversation and requesting a set of number plates with specific shapes. | 8th Jun 1939 | Box 148 \ 4 scan0269 | |
| Request to obtain one oblong front number plate and a set of registration letters and numbers. | 14th Jun 1939 | Box 148 \ 4 scan0270 | |
| Confirming a request to obtain pressed aluminium plates. | 23th Jun 1939 | Box 148 \ 4 scan0271 | |
| The design and costings for the Bentley V rear number plate. | 7th Jul 1939 | Box 148 \ 4 scan0272 | |
| Use of separate number plates for foreign versus English orders, arguing against them for the latter. | 7th Jul 1939 | Box 148 \ 4 scan0273 | |
| Approving the 'built-on' Cornercroft back numberplate for the Bentley V. | 11th Jul 1939 | Box 148 \ 4 scan0274 | |
| The order of a front aluminium number plate. | 2nd Oct 1939 | Box 148 \ 4 scan0275 | |
| Order for letters and numbers for a built-in rear number plate for chassis 33.G.7. | 2nd Oct 1939 | Box 148 \ 4 scan0276 | |
| Request to obtain letters and numbers RC.7846 from Messrs. Cornercroft for a built-in rear number plate. | 6th Nov 1939 | Box 148 \ 4 scan0277 | |
| Request to obtain one front number plate in pressed aluminium from Messrs. Homo Ltd. | 6th Nov 1939 | Box 148 \ 4 scan0278 | |
| Request to obtain one pressed aluminum front number plate from Messrs. Homo Ltd. | 15th Nov 1939 | Box 148 \ 4 scan0279 | |
| Requesting the procurement of a Homo alum pressed front number plate and registration letters from Messrs. Cornercrofts. | 28th Nov 1939 | Box 148 \ 4 scan0280 | |
| Letter from Specialloid Limited to Rolls Royce proposing their piston designs and listing other vehicle and aircraft manufacturers who use their products. | 27th Jul 1934 | Box 148 \ 4 scan0281 | |
| Letter from Specialloid Limited regarding satisfactory piston tests and offering their facilities for further engine testing. | 27th Jul 1934 | Box 148 \ 4 scan0282 | |
| Letter to Specialloid Limited regarding a drawing of a standard split skirt Bentley piston. | 30th Jul 1934 | Box 148 \ 4 scan0283 | |
| Letter from piston manufacturer Specialloid Limited requesting further design details. | 1st Aug 1934 | Box 148 \ 4 scan0284 | |
| Letter from Specialloid Limited regarding experimental pistons and associated drawings. | 2nd Aug 1934 | Box 148 \ 4 scan0285 | |
| Letter from piston manufacturer Specialloid Limited regarding the design and performance of their pistons. | 22th Sep 1934 | Box 148 \ 4 scan0286 | |
| Technical letter from Specialloid Limited discussing piston design, heat conduction, and clearances. | 22th Sep 1934 | Box 148 \ 4 scan0287 | |
| From Specialloid Limited detailing piston manufacturing and the properties of Specialloid Y alloy. | 22th Sep 1934 | Box 148 \ 4 scan0288 | |
| Letter from Specialloid Limited detailing the mechanical properties, manufacturing process, and performance of their Y alloy for piston purposes. | 22th Sep 1934 | Box 148 \ 4 scan0289 | |
| Letter from Specialloid Limited detailing severe piston bench test conditions. | 22th Sep 1934 | Box 148 \ 4 scan0290 | |
| Letter from Specialloid Limited detailing piston testing procedures and performance. | 22th Sep 1934 | Box 148 \ 4 scan0291 | |
| Report from Specialloid Limited detailing piston wear measurements after 53,990.4 miles. | 22th Sep 1934 | Box 148 \ 4 scan0292 | |
| Letter from Specialloid Limited detailing three-quarter section samples for Invicta, Buick, and Delage engines. | 22th Sep 1934 | Box 148 \ 4 scan0293 | |
| Letter to Specialloid Limited returning sample pistons and requesting a weight estimate. | 24th Sep 1934 | Box 148 \ 4 scan0294 | |
| Letter from Specialloid Limited regarding the Alumilite treatment process for pistons. | 24th Sep 1934 | Box 148 \ 4 scan0295 | |
| Piston treatment process to create a dense, porous oxide skin. | 24th Sep 1934 | Box 148 \ 4 scan0296 | |
| Letter from Specialloid Limited regarding the properties and testing of a treated Piston. | 24th Sep 1934 | Box 148 \ 4 scan0297 | |
| Return of sample pistons to The Specialloid Piston Co. | 27th Sep 1934 | Box 148 \ 4 scan0298 | |
| Letter from Specialloid Limited requesting clarification on piston design details to complete their drawing. | 28th Sep 1934 | Box 148 \ 4 scan0299 | |
| Page 2 of a letter from Specialloid Limited concerning piston weight and arrangements for bench and road testing. | 28th Sep 1934 | Box 148 \ 4 scan0300 | |
| Engineering drawing for a Specialloid R88 piston for a 6-cylinder Bentley engine. | 26th Sep 1934 | Box 148 \ 4 scan0301 | |
| Letter to Messrs. Specialloid Ltd. providing particulars regarding piston details and gudgeon pin specifications. | 3rd Oct 1934 | Box 148 \ 4 scan0302 | |
| Letter from Specialloid Limited regarding the manufacture of pistons for test purposes. | 4th Oct 1934 | Box 148 \ 4 scan0303 | |
| Advertisement for Specialloid Pistons highlighting their features and benefits. | 4th Oct 1934 | Box 148 \ 4 scan0304 | |
| Advertisement for 'The Universal Specialloid Piston' highlighting its alloy and oil consumption benefits. | 8th Oct 1934 | Box 148 \ 4 scan0305 | |
| Letter to Specialloid Limited regarding the cost and testing schedule for experimental piston dies. | 8th Oct 1934 | Box 148 \ 4 scan0306 | |
| Letter from Specialloid Limited concerning the supply of Specialloid Pistons and enclosing an R.88 drawing. | 20th Oct 1934 | Box 148 \ 4 scan0307 | |
| Technical drawing of a Specialloid Y Alloy piston for a 6-cylinder engine. | 26th Sep 1941 | Box 148 \ 4 scan0308 | |
| Letter to Specialloid Limited discussing piston clearance issues and anodical treatment development. | 23th Oct 1934 | Box 148 \ 4 scan0309 | |
| Letter from Specialloid Ltd. discussing piston clearances, measurements, and testing. | 26th Oct 1934 | Box 148 \ 4 scan0310 | |
| Letter from Specialloid Limited regarding anodical surface treatment and oil impregnation. | 26th Oct 1934 | Box 148 \ 4 scan0311 | |
| Letter to Specialloid Ltd. accepting pistons with suggested clearances on the condition that they are anodically treated. | 30th Oct 1934 | Box 148 \ 4 scan0312 | |
| Letter from Specialloid Limited confirming the supply of test pistons. | 1st Nov 1934 | Box 148 \ 4 scan0313 | |
| Letter confirming the dispatch date for six test pistons. | 5th Nov 1934 | Box 148 \ 4 scan0314 | |
| Letter from Specialloid Limited regarding the testing and supply of R.88 pistons. | 16th Jan 1935 | Box 148 \ 4 scan0315 | |
| Testing Specialloid Pistons in a Bentley engine, detailing performance, issues with knocking, and a subsequent piston seizure. | 11th Feb 1935 | Box 148 \ 4 scan0316 | |
| Performance graph for Specialloid Pistons, showing BHP and BMEP against RPM. | 13th Feb 1935 | Box 148 \ 4 scan0317 | |
| The trial of Bentley pistons submitted by Specialloid Limited, detailing issues found during testing. | 13th Feb 1935 | Box 148 \ 4 scan0318 | |
| Letter to Specialloid Ltd. regarding the testing of pistons and the despatch of two sets. | 22th Apr 1936 | Box 148 \ 4 scan0319 | |
| Letter to Specialloid Ltd. regarding pistons and the inability to carry out tests due to work pressures. | 23th Apr 1937 | Box 148 \ 4 scan0320 | |
| Letter from Specialloid Limited regarding a delay in piston tests and a request for drawings. | 24th Apr 1937 | Box 148 \ 4 scan0321 | |
| Letter to Specialloid Ltd. regarding the supply of piston drawing E60632 for a 4¼ litre Bentley and declining to test their solid skirt type pistons. | 30th Aug 1937 | Box 148 \ 4 scan0322 | |
| Letter from Specialloid Limited regarding piston designs and drawings for a 4 1/4 litre Bentley. | 31th Aug 1937 | Box 148 \ 4 scan0323 | |
| Letter from piston manufacturer Specialloid seeking clarification on piston specifications for Bentley and Rolls Royce models. | 3rd Sep 1937 | Box 148 \ 4 scan0324 | |
| Letter to Specialloid Ltd. clarifying cylinder size, piston dimensions, and gudgeon pin fitment for a 4 1/4 litre Bentley. | 7th Sep 1937 | Box 148 \ 4 scan0325 | |
| Letter to Specialloid Ltd. declining the use of their pistons for Bentley Motors service purposes due to a lack of extensive testing. | 30th Sep 1937 | Box 148 \ 4 scan0326 | |
| Letter fragment discussing further designs of pistons and follow-up correspondence. | 21th Oct 1937 | Box 148 \ 4 scan0327 | |
| Letter from Specialloid Limited requesting permission to fit their own brand of pistons into a Bentley and keep the guarantee valid. | 21th Oct 1937 | Box 148 \ 4 scan0328 | |
| Letter to Specialloid Limited declining to guarantee a Bentley engine fitted with their non-standard pistons. | 25th Oct 1937 | Box 148 \ 4 scan0329 | |
| Letter from piston manufacturer Specialloid Limited to W. A. Robotham regarding fitting their pistons to a Bentley car. | 28th Oct 1937 | Box 148 \ 4 scan0330 | |
| Letter from Specialloid Limited to W. A. Rowbotham arranging a meeting with their designer in Derby. | 28th Oct 1937 | Box 148 \ 4 scan0331 | |
| Letter to Specialloid Limited regarding the testing of their pistons and clarifying guarantee terms. | 30th Oct 1937 | Box 148 \ 4 scan0332 | |
| Confirming instructions that experimental cars must be checked before trials or release to other departments. | 1st Sep 1924 | Box 148 \ 5 scan0001 | |
| New fortnightly reporting scheme for the Experimental Department and the production of a 20 HP chassis for a 10,000-mile test. | 17th Jun 1925 | Box 148 \ 5 scan0002 | |
| The timing of critic reviews and a proposal for a standard 10,000-mile test for new parts and cars. | 4th Jun 1926 | Box 148 \ 5 scan0003 | |
| Testing procedures, suggestions versus instructions, and the frequency of card index system updates. | 4th Jun 1926 | Box 148 \ 5 scan0004 | |
| Proposed procedure for a 10,000-mile vehicle test. | 18th Jun 1926 | Box 148 \ 5 scan0005 | |
| Clarifying a misunderstanding regarding the 10,000-mile testing procedure for a 20 HP chassis between the Experimental and Sales departments. | 18th Jun 1926 | Box 148 \ 5 scan0006 | |
| And clarifying vehicle testing procedures, including a 10,000-mile test and an Alpine pass run. | 18th Jun 1926 | Box 148 \ 5 scan0007 | |
| Proposal for 10,000-mile tests in France, including challenges with a new lightened front axle on a Phantom car. | 21th Jun 1926 | Box 148 \ 5 scan0008 | |
| Planning for a 10,000-mile car test, including potential delays for sales feedback and proposals for additional Alpine pass tests. | 21th Jun 1926 | Box 148 \ 5 scan0009 | |
| The collection and modification of a 20 HP car for experimental testing. | 29th Sep 1925 | Box 148 \ 5 scan0010 | |
| Scope and arrangements for the 10,000 miles vehicle tests. | 29th Sep 1925 | Box 148 \ 5 scan0011 | |
| Efficiency of a .940 worm and 1800 lbs. side steering tube springs in alleviating road shocks. | 21th Jun 1926 | Box 148 \ 5 scan0012 | |
| Vehicle testing procedures for chassis, steering components, and hydraulic shock dampers. | 21th Jun 1926 | Box 148 \ 5 scan0013 | |
| Steering improvements, high-speed wobbles, road shocks, and hydraulic dampers. | 21th Jun 1926 | Box 148 \ 5 scan0014 | |
| Report discussing the selection of springs, semi-balloon tyres, and shock damper oil based on performance requirements and trial results. | 4th Jun 1926 | Box 148 \ 5 scan0015 | |
| Duplication of experimental work and referencing an attached document. | 4th Jun 1926 | Box 148 \ 5 scan0016 | |
| Comparative tests on steering, tyres, and suspension for an Open Touring Car and an Open White Riviera Car. | 4th Jun 1926 | Box 148 \ 5 scan0017 | |
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