| Description | Date | Identifier | |
| Letter from the Experimental Department to a supplier regarding specifications for special pistons. | 15th Jan 1940 | Box 148 \ 1 scan0230 | |
| Request to send a purchase order to The Light Production Co. Ltd. for 18 pistons. | 15th Jan 1940 | Box 148 \ 1 scan0231 | |
| Letter to The Light Production Co. Ltd. regarding piston dimensions, weight reduction, and core boxes. | 22th Jan 1940 | Box 148 \ 1 scan0232 | |
| Letter to The Light Production Co. Ltd. regarding revised drawings for high crown pistons and placing an interim order. | 17th Feb 1940 | Box 148 \ 1 scan0233 | |
| Letter to The Light Production Co. Ltd. discussing the use of a lightened split skirt piston and proposing tests with magnesium. | 21th Feb 1940 | Box 148 \ 1 scan0234 | |
| Letter offering to cooperate on casting work from dies. | 21th Feb 1940 | Box 148 \ 1 scan0235 | |
| Letter from 'The Motor' magazine requesting test data on piston friction and proposing a collaboration for an article on luxury cars. | 23th Feb 1940 | Box 148 \ 1 scan0236 | |
| Request to produce detail drawings for three new split skirt pistons with specific design particulars. | 28th Feb 1940 | Box 148 \ 1 scan0237 | |
| Letter to The Light Production Co. Ltd. concerning split skirt pistons and placing an order for various pistons and rings. | 4th Mar 1940 | Box 148 \ 1 scan0238 | |
| Letter to L. Pomeroy of 'The Motor' magazine comparing Aerolite and split skirt pistons. | 4th Mar 1940 | Box 148 \ 1 scan0239 | |
| Continued letter regarding the standardisation of piston types for post-war conditions and a meeting about an article. | 8th Mar 1940 | Box 148 \ 1 scan0240 | |
| Performance comparison chart between Aerolite and E.B. 1299 pistons, showing B.HP and B.M.E.P. against R.P.M. | 22th Mar 1938 | Box 148 \ 1 scan0241 | |
| Request to send an order to The Light Production Co. for pistons and rings. | 4th Mar 1940 | Box 148 \ 1 scan0242 | |
| Letter to L. Pomeroy of 'The Motor' magazine to rearrange a meeting. | 5th Mar 1940 | Box 148 \ 1 scan0243 | |
| Letter to The Light Production Co. Ltd. requesting blueprints for piston rings due to a re-design. | 8th Mar 1940 | Box 148 \ 1 scan0244 | |
| Letter from the Technical Editor of 'The Motor' magazine to W. A. Robotham proposing to postpone a meeting until after Easter. | 9th Mar 1940 | Box 148 \ 1 scan0245 | |
| Letter to L. Pomeroy, Technical Editor of 'The Motor', confirming arrangements for a visit. | 11th Mar 1940 | Box 148 \ 1 scan0246 | |
| Letter from Laurence Pomeroy, Technical Editor of 'The Motor' magazine, to W.A. Robotham postponing a meeting. | 12th Mar 1940 | Box 148 \ 1 scan0247 | |
| Index card for Piston Ring Tests concerning W.3. No. 4. Unit. | 16th Mar 1940 | Box 148 \ 1 scan0248 | |
| Order for Piston Rings be sent to Messrs. Hepworth & Grandage, Ltd. | 19th Mar 1940 | Box 148 \ 1 scan0249 | |
| Request to issue an order to Light Production Co. Ltd. for parts mentioned in an attached advice note. | 1st Apr 1940 | Box 148 \ 1 scan0250 | |
| Alteration note changing the piston ring specification from 212A to 4K6 for various models. | 8th Apr 1940 | Box 148 \ 1 scan0251 | |
| Letter to Messrs. Light Production Co, Ltd. regarding revised drawings for split skirt pistons. | 22th Apr 1940 | Box 148 \ 1 scan0252 | |
| Request to produce and supply three different parts with specific quantities. | 22th Apr 1940 | Box 148 \ 1 scan0253 | |
| Letter from the Experimental Department regarding revised drawings and specifications for split skirt pistons. | 22th Apr 1940 | Box 148 \ 1 scan0254 | |
| Request to produce and supply quantities of specific parts. | 22th Apr 1940 | Box 148 \ 1 scan0255 | |
| Letter from the Experimental Department regarding revised drawings for split skirt pistons. | 22th Apr 1940 | Box 148 \ 1 scan0256 | |
| Request to produce and supply specific parts identified by reference numbers. | 22th Apr 1940 | Box 148 \ 1 scan0257 | |
| Request to send a purchase order for different quantities of pistons to The Light Production Co. Ltd. | 22th Apr 1940 | Box 148 \ 1 scan0258 | |
| Letter to Light Production Co. Ltd. enclosing previously omitted drawings. | 25th Apr 1940 | Box 148 \ 1 scan0259 | |
| Letter from The Light Production Co. Ltd. chasing missing drawings for Split Skirt Pistons. | 26th Apr 1940 | Box 148 \ 1 scan0260 | |
| Letter from The Light Production Co. Ltd. regarding the supply of seven oversized Pistons E.B.3365. | 1st May 1940 | Box 148 \ 1 scan0261 | |
| Letter from The Light Production Co. Ltd. to the Experimental Department regarding piston design and grinding fixtures. | 3rd May 1940 | Box 148 \ 1 scan0262 | |
| Request to place an order for 7 pistons with The Light Production Co. Ltd. | 7th May 1940 | Box 148 \ 1 scan0263 | |
| Inquiry to Light Production Co. Ltd. regarding the material specifications for gudgeon pins on the Bentley V. | 8th May 1940 | Box 148 \ 1 scan0264 | |
| Letter to The Light Production Co. Ltd. concerning the machining of spigots and the grinding of split skirt pistons. | 9th May 1940 | Box 148 \ 1 scan0265 | |
| Letter to The Light Production Co., Ltd. regarding the special grinding and delivery of split skirt pistons. | 13th May 1940 | Box 148 \ 1 scan0266 | |
| Confirming arrangements for grinding on experimental chassis pistons. | 13th May 1940 | Box 148 \ 1 scan0267 | |
| Letter to Wellworthy Piston Rings Ltd. regarding Leyland big-end failures, confirming the cause as oil shortage. | 17th May 1940 | Box 148 \ 1 scan0268 | |
| Letter from The Light Production Co. Ltd. regarding the grinding and delivery of split skirt pistons. | 21th May 1940 | Box 148 \ 1 scan0269 | |
| Letter to The Light Production Co. Ltd. regarding piston order facilities and keeping the order open. | 17th Jul 1940 | Box 148 \ 1 scan0270 | |
| Letter from The Light Production Co. Ltd. regarding the delivery schedule for pistons. | 23th Jul 1940 | Box 148 \ 1 scan0271 | |
| The receipt of split skirt chassis pistons from the Light Production Co. for post-war development engines. | 16th Aug 1940 | Box 148 \ 1 scan0272 | |
| Comparing two types of high power cylinder heads regarding detonation and compression ratio. | 9th Sep 1940 | Box 148 \ 1 scan0273 | |
| Authorising payment for foundry charges related to pistons. | 11th Sep 1940 | Box 148 \ 1 scan0274 | |
| Charges for foundry equipment related to pistons and seeking approval. | 9th Sep 1940 | Box 148 \ 1 scan0275 | |
| Reference note regarding big end bearings from an experimental car sent to Wellworthy Pistons Ltd. | 25th Sep 1940 | Box 148 \ 1 scan0276 | |
| Weight and dimensional discrepancies in rationalised pistons supplied by Aerolite. | 18th Sep 1940 | Box 148 \ 1 scan0277 | |
| The despatch of two different pistons to The Light Production Co. Ltd. | 23th Oct 1940 | Box 148 \ 1 scan0278 | |
| Letter to The Light Production Co. regarding the supply and design of 3.250' and 2.50' bore pistons. | 24th Oct 1940 | Box 148 \ 1 scan0279 | |
| Letter to a supplier discussing the development and production of different types of pistons. | 5th Nov 1940 | Box 148 \ 1 scan0280 | |
| Page 2 of a letter requesting feedback on a submitted drawing and permission to proceed with making 36 pistons. | 5th Nov 1940 | Box 148 \ 1 scan0281 | |
| Request for the chemical analysis of 8 cast iron rings, with one undergoing a full analysis and the others checked for consistency. | 9th Nov 1940 | Box 148 \ 1 scan0282 | |
| Reminding the recipient about an order for 3 3/4 bore pistons. | 12th Nov 1940 | Box 148 \ 1 scan0283 | |
| Letter from the Experimental Department requesting sample pistons with specific dimensions and weights. | 16th Nov 1940 | Box 148 \ 1 scan0284 | |
| Request to detail a 3.750' diameter piston for the largest bore version of the six-cylinder range. | 18th Nov 1940 | Box 148 \ 1 scan0285 | |
| Letter from a supplier regarding the production and supply of different sized pistons. | 19th Nov 1940 | Box 148 \ 1 scan0286 | |
| Report on failed oil pumps from an A.I.D. test, with a warning to the Assembly Shop about part interchangeability. | 21th Nov 1940 | Box 148 \ 1 scan0287 | |
| Investigating the fitting of an incorrect idler gear and bracket to engine K8417. | 18th Nov 1940 | Box 148 \ 1 scan0288 | |
| Alterations to an exhaust pipe and air scoop, and investigating cracking in air intakes. | 3rd Sep 1929 | Box 148 \ 1 scan0289 | |
| Comparison photograph of Special Ratio and Standard Ratio gear and bracket assemblies for the Kestrel engine. | 25th Nov 1940 | Box 148 \ 1 scan0290 | |
| Letter to The Light Production Co. Ltd. regarding the elliptical grinding and machining of 7 light pistons. | 25th Nov 1940 | Box 148 \ 1 scan0291 | |
| Letter from the Experimental Department to The Light Production Co. Ltd. requesting the manufacture of 36 pistons. | 26th Nov 1940 | Box 148 \ 1 scan0292 | |
| Order for 36 pistons to be sent to The Light Production Co., with a note to update the correspondence address. | 26th Nov 1940 | Box 148 \ 1 scan0293 | |
| Request to The Light Production Co. Ltd. for a quote and lead time for 26 pistons for a 12-cylinder vee engine. | 10th Dec 1940 | Box 148 \ 1 scan0294 | |
| Follow-up letter to The Light Production Co. Ltd. regarding lighter pistons and requesting the material specification for piston rings. | 19th Dec 1940 | Box 148 \ 1 scan0295 | |
| Letter to The Light Production Co., Ltd. regarding the urgent supply of pistons for a trial test, suggesting material RR.53. | 20th Dec 1940 | Box 148 \ 1 scan0296 | |
| Letter to The Light Production Co. regarding the manufacture and grinding of 36 pistons. | 21th Dec 1940 | Box 148 \ 1 scan0297 | |
| Order to be placed for 40 pistons with The Light Production Co. Ltd. | 31th Dec 1940 | Box 148 \ 1 scan0298 | |
| Letter to Messrs. Hepworth & Grandage Ltd. regarding a composite piston drawing. | 2nd Jan 1941 | Box 148 \ 1 scan0299 | |
| Letter to The Light Production Co. Ltd. authorising the manufacture of 40 LM.101 pistons and discussing procedures. | 28th Dec 1940 | Box 148 \ 1 scan0300 | |
| Letter concerning the delayed delivery of 36 pistons pending the approval of a casting drawing. | 17th Dec 1940 | Box 148 \ 1 scan0301 | |
| Letter from The Light Production Co. Ltd. regarding a delay in piston production for order number 36316. | 17th Dec 1940 | Box 148 \ 1 scan0302 | |
| Letter from a piston manufacturer discussing the inability to find a suitable stock piston and proposing a custom design. | 27th Dec 1940 | Box 148 \ 1 scan0303 | |
| Continuation of a letter from Hepworth & Grandage Ltd. regarding a proposed solution. | 7th Jan 1941 | Box 148 \ 1 scan0304 | |
| Letter from Hepworth & Grandage Ltd. regarding a piston drawing and a proposed composite design. | 7th Jan 1941 | Box 148 \ 1 scan0305 | |
| The parts list for a 3 3/4 inch diameter piston assembly under a rationalised programme. | 8th Jan 1941 | Box 148 \ 1 scan0306 | |
| Urgent request to Wellworthy Pistons Ltd. for the machining of 24 special low compression pistons for the Merlin engine. | 9th Jan 1941 | Box 148 \ 1 scan0307 | |
| Letter to The Light Production Co. Ltd. concerning the manufacturing process and specifications for lighter split skirt pistons. | 11th Feb 1941 | Box 148 \ 1 scan0308 | |
| Letter from The Light Production Co. Ltd. regarding the despatch of seven pistons. | 17th Jan 1941 | Box 148 \ 1 scan0309 | |
| Letter from The British Piston Ring Co Ltd requesting cylinder wear results for previously supplied inserts. | 17th Jan 1941 | Box 148 \ 1 scan0310 | |
| Letter from High Duty Alloys Ltd. regarding the supply of 18 piston blanks and a related drawing. | 27th Jan 1941 | Box 148 \ 1 scan0311 | |
| Letter to The Light Production Co. Ltd. regarding the delivery schedule for special piston LM.101. | 30th Jan 1941 | Box 148 \ 1 scan0312 | |
| Letter from Wellworthy Piston Rings Limited apologizing for a delay in supplying 24 special pistons due to issues with forgings. | 1st Feb 1941 | Box 148 \ 1 scan0313 | |
| Letter from Wellworthy Piston Rings Limited acknowledging a previous letter and awaiting further advice. | 3rd Feb 1941 | Box 148 \ 1 scan0314 | |
| Invoice from Light Production Co. Ltd for pistons and the need for a covering order. | 25th Feb 1941 | Box 148 \ 1 scan0315 | |
| Letter to The British Piston Ring Co. Ltd. explaining the curtailment of experimental work due to the war. | 2nd Mar 1941 | Box 148 \ 1 scan0316 | |
| Letter to The Light Production Co. Ltd. regarding the production and delivery of pistons. | 11th Mar 1941 | Box 148 \ 1 scan0317 | |
| The use of 24 special piston blanks for Merlin engine production by Wellworthy Piston Rings Ltd. | 13th Mar 1941 | Box 148 \ 1 scan0318 | |
| Letter to Wellworthy Ltd. regarding piston design improvements, referencing drawings LM.449 and LM.101. | 12th Apr 1941 | Box 148 \ 1 scan0319 | |
| Request to Light Production Company for delivery dates and quantities to Wellworthy, noted as having been phoned. | 16th Apr 1941 | Box 148 \ 1 scan0320 | |
| Letter concerning the modification and weight reduction of split skirt pistons. | 1st May 1941 | Box 148 \ 1 scan0321 | |
| Letter from Wellworthy Piston Rings Ltd. discussing the production of pistons and carburetors, and recommending pressed components over castings. | 9th May 1941 | Box 148 \ 1 scan0322 | |
| Letter from the Managing Director stating a preference for pressing over die-casting for pistons. | 9th May 1941 | Box 148 \ 1 scan0323 | |
| Letter from High Duty Alloys Ltd. discussing the use of pressed pistons for Merlin engines. | 12th May 1941 | Box 148 \ 1 scan0324 | |
| Letter discussing a setback with AC.9 connecting rod bearing experiments which resulted in a split bearing. | 26th May 1941 | Box 148 \ 1 scan0325 | |
| Letter from Wellworthy Piston Rings Ltd. discussing potential failures in casting, material or physical properties. | 26th May 1941 | Box 148 \ 1 scan0326 | |
| Letter to Wellworthy Piston Rings requesting three sets of LM. 319 pistons to be machined from standard Merlin blanks. | 3rd Jun 1941 | Box 148 \ 1 scan0327 | |
| Letter to The Light Production Co. Ltd. regarding a correction to the weight of a 3.5 inch diameter piston, part RR.786. | 3rd Jun 1941 | Box 148 \ 1 scan0328 | |
| Letter from Wellworthy Piston Rings Ltd. to W. A. Robotham confirming a decision not to purchase a car. | 30th May 1941 | Box 148 \ 1 scan0329 | |
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