| Description | Date | Identifier | |
| Request to pack and despatch oil samples to Simmonds Aerocessories in London. | 3rd Nov 1938 | Box 136 \ 3 scan0009 | |
| Letter to Simmonds Aerocessories Ltd. regarding Fram oil filters, forwarding oil samples for analysis and requesting quotations. | 3rd Nov 1938 | Box 136 \ 3 scan0010 | |
| Letter to Simmonds Aerocessories Ltd. regarding component specifications. | 3rd Nov 1938 | Box 136 \ 3 scan0011 | |
| Requesting parts to be sent to Paris for fitting 'GENERAL' oil filters to two cars. | 8th Nov 1938 | Box 136 \ 3 scan0012 | |
| Replying to a request for parts for the housing of a 'General' filter on two B.11 cars. | 8th Nov 1938 | Box 136 \ 3 scan0013 | |
| Letter from British Filters Ltd. regarding the supply and standardization of a General Filter. | 14th Nov 1938 | Box 136 \ 3 scan0014 | |
| Goods advice note from British Filters, Ltd. for the dispatch of one general filter. | 14th Nov 1938 | Box 136 \ 3 scan0015 | |
| Letter from British Filters Ltd. requesting a photograph of a filter fitted to a car for a leaflet and particulars of recent tests. | 14th Nov 1938 | Box 136 \ 3 scan0016 | |
| Letter to British Filters Ltd. regarding the use of a photograph and a performance report of their filter. | 15th Nov 1938 | Box 136 \ 3 scan0017 | |
| Decision to fit a General oil filter to the latter half of the 'E' series vehicles. | 21th Nov 1938 | Box 136 \ 3 scan0018 | |
| Letter requesting a supplier to send a filter and spare cartridges to the Paris Depot. | 24th Nov 1938 | Box 136 \ 3 scan0019 | |
| Letter from British Filters Ltd. confirming the despatch of a filter and spare cartridges. | 25th Nov 1938 | Box 136 \ 3 scan0020 | |
| Letter from British Filters Ltd. regarding the return of a Fram Filter and a request for a case to test a cartridge. | 10th Dec 1938 | Box 136 \ 3 scan0021 | |
| Goods advice note from British Filters Ltd. for a Fram Filter. | 9th Dec 1938 | Box 136 \ 3 scan0022 | |
| Internal memorandum updating oil draining intervals for vehicles fitted with 'General' filters. | 14th Dec 1938 | Box 136 \ 3 scan0023 | |
| Petrol and oil filtration systems, specifically concerning Flexofiltration Limited. | 19th Dec 1938 | Box 136 \ 3 scan0024 | |
| Flexo filter and contacting Flexo Works. | 19th Dec 1938 | Box 136 \ 3 scan0025 | |
| Letter from British Filters Ltd. regarding requests to supply and fit filters to Rolls-Royce and Bentley cars. | 21th Dec 1938 | Box 136 \ 3 scan0026 | |
| Letter to British Filters Ltd. regarding the adaptation of a filter for a pre-takeover 6 1/2 litre Bentley. | 29th Dec 1938 | Box 136 \ 3 scan0027 | |
| Letter from British Filters Ltd. regarding the adaptation of a filter for a 6.5 litre Bentley and requesting old oil for testing. | 30th Dec 1938 | Box 136 \ 3 scan0028 | |
| Request to collect and despatch 10 gallons of dirty engine oil for filtration tests. | 2nd Jan 1939 | Box 136 \ 3 scan0029 | |
| Complaint about rust on filters from the British Filter Co. and proposed remedial actions. | 6th Jan 1939 | Box 136 \ 3 scan0030 | |
| Outlining five required improvements for the 'General' filter as standardised on the Wraith model. | 16th Jan 1939 | Box 136 \ 3 scan0031 | |
| Order for 2 dozen Tecalemit filters for experimental chassis unit test beds. | 31th Jan 1939 | Box 136 \ 3 scan0032 | |
| Letter to British Filters Ltd. regarding quality issues with returned filters and requesting samples for rig testing. | 2nd Feb 1939 | Box 136 \ 3 scan0033 | |
| Letter from British Filters Ltd regarding enamel finish issues and the dispatch of American and English sample cartridges. | 4th Feb 1939 | Box 136 \ 3 scan0034 | |
| Requesting an official order for two filter elements from British Filters Ltd. for comparative testing. | 7th Feb 1939 | Box 136 \ 3 scan0035 | |
| Request to despatch a model filter case and oil samples to British Filters Ltd. | 10th Feb 1939 | Box 136 \ 3 scan0036 | |
| Letter to British Filters Ltd. regarding the return of a filter case and comparative oil filter samples. | 10th Feb 1939 | Box 136 \ 3 scan0037 | |
| The purchase of filter elements and glass thermometers. | 24th Feb 1939 | Box 136 \ 3 scan0038 | |
| Letter to supplier British Filters Ltd. regarding faults found on rejected filters. | 18th Mar 1939 | Box 136 \ 3 scan0039 | |
| Follow-up letter from Luber-finer (England) Ltd. regarding an enquiry about fitting their product to a Phantom II Rolls. | 13th Apr 1939 | Box 136 \ 3 scan0040 | |
| Letter addressed to Luber-Finer (England) Ltd. concerning previous correspondence. | 14th Apr 1939 | Box 136 \ 3 scan0041 | |
| Request for a simplified design for a filler located in the rocker cover. | 24th Apr 1939 | Box 136 \ 3 scan0042 | |
| Letter from Stream-Line Filters Limited regarding their new self-heating, self-cleaning MC7 filter for Wraith models. | 29th Apr 1939 | Box 136 \ 3 scan0043 | |
| Letter to a filter supplier regarding previous tests on by-pass filters and the requirements for testing a new article. | 1st May 1939 | Box 136 \ 3 scan0044 | |
| Letter from Stream-Line Filters Limited regarding the advantages of their by-pass filters for Diesel engines. | 3rd May 1939 | Box 136 \ 3 scan0045 | |
| The procurement of piston rings, bearings, and filters from various suppliers for trial. | 11th May 1939 | Box 136 \ 3 scan0046 | |
| Results of extended comparative tests on 'Fram' and 'General' oil reconditioner filters. | 31th May 1939 | Box 136 \ 3 scan0047 | |
| Letter from Automotive Products Company Ltd regarding the design of by-pass type oil filters with a replaceable element. | 31th May 1939 | Box 136 \ 3 scan0048 | |
| Letter from Simmonds Aerocessories Ltd regarding the Simmonds Fram Oil and Engine Cleaner and a request for larger oil samples. | 12th Jun 1939 | Box 136 \ 3 scan0049 | |
| Letter from Simmonds Aerocessories Limited proposing a meeting to discuss Fram Cleaners. | 12th Jun 1939 | Box 136 \ 3 scan0050 | |
| Request to return a sample stamping submitted by British Filters Ltd. for size approval. | 14th Jun 1939 | Box 136 \ 3 scan0051 | |
| Cover letter to British Filters Ltd. regarding a confidential report on a protracted road test of their filter. | 14th Jun 1939 | Box 136 \ 3 scan0052 | |
| Reducing the recommended oil filter change interval from 10,000 to 5,000 miles for Wraith III and B.V. chassis. | 21th Jun 1939 | Box 136 \ 3 scan0053 | |
| Brief letter to T.C. Worth of British Filters Ltd. regarding an attached copy of a letter sent to Helmore. | 24th Jun 1939 | Box 136 \ 3 scan0054 | |
| Brief typed message from Robotham confirming a change of meeting time and place. | 27th Jun 1939 | Box 136 \ 3 scan0055 | |
| Cover memo from Rm. to W/Hucknall Dor. regarding an attached copy of a letter written to Worth. | 30th Jun 1939 | Box 136 \ 3 scan0056 | |
| Letter to T.C. Worth of British Filters Ltd. arranging a visit to discuss filters and corrosion protection. | 30th Jun 1939 | Box 136 \ 3 scan0057 | |
| Letter from the Experimental Dept. requesting one dozen General filter elements be sent to France. | 24th Jul 1939 | Box 136 \ 3 scan0058 | |
| Request to send an order for 12 General filter elements to British Filters Ltd. | 24th Jul 1939 | Box 136 \ 3 scan0059 | |
| Internal request to order Tecalemit filters for use on experimental test beds. | 3rd Oct 1939 | Box 136 \ 3 scan0060 | |
| Retrospectively fitting General Filters to various car chassis. | 17th Jan 1940 | Box 136 \ 3 scan0061 | |
| Arranging a weekend visit to the Derby works to gather information for the layout of a strip and assembly shop. | 23th Jan 1940 | Box 136 \ 3 scan0062 | |
| Letter to T.C. Worth of British Filters Ltd. regarding filters for test beds at Glasgow and a potential meeting. | 25th Jan 1939 | Box 136 \ 3 scan0063 | |
| Letter from British Filters Ltd regarding a late letter concerning Swindell's visit. | 29th Jan 1940 | Box 136 \ 3 scan0064 | |
| Requesting oil samples from experimental cars to test filter change intervals. | 9th Feb 1940 | Box 136 \ 3 scan0065 | |
| Request for parts to fit a 3½ Bentley unit with a general filter for experimental purposes. | 21th Feb 1940 | Box 136 \ 3 scan0066 | |
| New blueprints for the Bentley II General Oil Filter. | 22th Feb 1940 | Box 136 \ 3 scan0067 | |
| Request for one complete floating oil intake to be supplied to an office. | 25th Feb 1940 | Box 136 \ 3 scan0068 | |
| Instructing stores to despatch a Floating Oil Intake to T.C. Worth and to charge him for it. | 28th Feb 1940 | Box 136 \ 3 scan0069 | |
| Invitation to T.C. Worth to discuss business matters, including Diesel fuel oil filtration. | 29th Feb 1940 | Box 136 \ 3 scan0070 | |
| Internal order request for fitter replacement elements and an A.C. filter unit. | 1st Mar 1940 | Box 136 \ 3 scan0071 | |
| Requesting a test on two Phantom III oil filters to check back pressure. | 18th Mar 1940 | Box 136 \ 3 scan0072 | |
| Request to British Filters Ltd. for the supply of a dozen General Filters and a drawing. | 19th Mar 1940 | Box 136 \ 3 scan0073 | |
| Letter from British Filters Ltd confirming the dispatch of one dozen 2ARR General Filters. | 21th Mar 1940 | Box 136 \ 3 scan0074 | |
| Engine failure due to a clogged petrol filter, leading to a suggestion for a new post-war service scheme. | 1st Apr 1940 | Box 136 \ 3 scan0075 | |
| Organisational issues regarding car security, tool management, and servicing within the Experimental Department. | 2nd Apr 1940 | Box 136 \ 3 scan0076 | |
| New drawings and parts for a general bypass filter on the 25/30 and B.II chassis. | 3rd Apr 1940 | Box 136 \ 3 scan0077 | |
| Request to send an order for 12 complete filters to British Filters Ltd. | 16th Apr 1940 | Box 136 \ 3 scan0078 | |
| The arrangement for fitting general filters to Bentley and Rolls Royce cars. | 19th Jun 1940 | Box 136 \ 3 scan0079 | |
| Poor workmanship of a replacement Filter Assembly for the Phantom III chassis from supplier W.H. Paul Ltd. | 19th Jul 1940 | Box 136 \ 3 scan0080 | |
| Sample Phantom III filter and the inability to perform flow testing due to a lack of facilities. | 24th Jul 1940 | Box 136 \ 3 scan0081 | |
| Letter responding to a query about the horsepower required to circulate engine oil. | 24th Jul 1940 | Box 136 \ 3 scan0082 | |
| Letter from British Filters Ltd thanking for information and photographs of bearings regarding oil circulation. | 26th Jul 1940 | Box 136 \ 3 scan0083 | |
| Request to British Filters Ltd. for a bye-pass filter suitable for a 10 HP car. | 16th Aug 1940 | Box 136 \ 3 scan0084 | |
| Letter from British Filters Ltd. regarding a filter for a 10 HP car. | 21th Aug 1940 | Box 136 \ 3 scan0085 | |
| Cover note from 'Rm.' attaching a copy of a letter written to T.C. Worth. | 25th Sep 1940 | Box 136 \ 3 scan0086 | |
| Letter to T.C. Worth discussing fuel filter design, comparing by-pass and full-flow systems. | 24th Sep 1940 | Box 136 \ 3 scan0087 | |
| Page two of a letter discussing filtration, a paper for the I.A.E., and bearing condition. | 24th Sep 1940 | Box 136 \ 3 scan0088 | |
| Requesting pressure drop tests on a Junkers pressure oil filter at various temperatures. | 18th Sep 1940 | Box 136 \ 3 scan0089 | |
| Request for various sizes of test tubes to be used for oil samples. | 10th Oct 1940 | Box 136 \ 3 scan0090 | |
| Letter from British Filters Ltd concerning a meeting about filters. | 30th Sep 1940 | Box 136 \ 3 scan0091 | |
| Exploded view of a component from a Mercedes-Benz DB 601 engine. | 30th Sep 1940 | Box 136 \ 3 scan0092 | |
| Letter from the Experimental Department to A.C. Sphinx Ltd. requesting data on bye-pass oil filters. | 23th Oct 1940 | Box 136 \ 3 scan0093 | |
| Cover note for an attached photograph and exploded drawing of a Junkers pressure oil pump and oil filter. | 23th Oct 1940 | Box 136 \ 3 scan0094 | |
| Disassembled view of filter components laid out on a board. | 9th Oct 1940 | Box 136 \ 3 scan0095 | |
| Exploded view drawing of a Junkers pressure oil pump. | 9th Oct 1940 | Box 136 \ 3 scan0096 | |
| Photograph showing the disassembled components of an oil pump. | 29th Oct 1940 | Box 136 \ 3 scan0097 | |
| Outlining the procedure and objectives for oil tests on experimental cars. | 29th Oct 1940 | Box 136 \ 3 scan0098 | |
| Instructions for engine oil and filter element sampling and replacement procedures. | 29th Oct 1940 | Box 136 \ 3 scan0099 | |
| Request for 24 white and black prints of an enclosed document regarding Oil Filter Elements. | 11th Nov 1940 | Box 136 \ 3 scan0100 | |
| Requisition form for blue prints of a chart, marked as very urgent. | 11th Nov 1940 | Box 136 \ 3 scan0101 | |
| Contribution to a paper on oil filtration, discussing engine wear, superfinishing, and filter performance. | 20th Nov 1940 | Box 136 \ 3 scan0102 | |
| The performance of oil filters and the need for research into the most economical and efficient options. | 20th Nov 1940 | Box 136 \ 3 scan0103 | |
| Letter discussing the problem of oil filters for a 27-litre engine, enclosing a drawing for a centrifugal filter. | 25th Nov 1940 | Box 136 \ 3 scan0104 | |
| Request from Simmonds Aerocessories for instruction books to assess fitting their FRAM By-Pass Oil Cleaner to engines. | 18th Nov 1940 | Box 136 \ 3 scan0105 | |
| Letter to T.C. Worth regarding forgotten oil samples being held for collection. | 27th Nov 1940 | Box 136 \ 3 scan0106 | |
| Invoice from The British Filters Ltd. for 'General Filters'. | 4th Dec 1940 | Box 136 \ 3 scan0107 | |
| Letter discussing three different oil samples to compare the effectiveness of a general filter versus no filter. | 4th Dec 1940 | Box 136 \ 3 scan0108 | |
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