| Description | Date | Identifier | |
| Incorrect delivery of Champion sparking plugs. | 10th Jun 1941 | Box 162 \ 3 img221 | |
| Order for two types of Champion Spark Plugs. | 17th Feb 1942 | Box 162 \ 3 img222 | |
| Correction notice regarding the correct type of Champion sparking plugs for the 20HP model. | 4th Feb 1937 | Box 162 \ 3 img223 | |
| Letter from K.L.G. Sparking Plugs regarding alterations to a pressed container and sending new model plugs for testing. | 28th Apr 1933 | Box 162 \ 4 img001 | |
| Letter from K.L.G. Sparking Plugs regarding the development and testing of a new experimental spark plug, number 765. | 28th Apr 1933 | Box 162 \ 4 img002 | |
| Letter from K.L.G. Sparking Plugs Limited concerning the provision of plugs for a car. | 28th Apr 1933 | Box 162 \ 4 img003 | |
| Letter to K.L.G. Sparking Plug Ltd requesting a design modification for the 765 Plugs. | 1st May 1933 | Box 162 \ 4 img004 | |
| Letter from K.L.G. Sparking Plugs Ltd. confirming a request to make the barrel of the K.L.G. 765 plug longer. | 2nd May 1933 | Box 162 \ 4 img005 | |
| Letter to K.L.G. Sparking Plugs Ltd. confirming the dimensions of a new plug (765.A) for a Bentley engine. | 11th May 1933 | Box 162 \ 4 img006 | |
| Results of engine performance tests using different spark plugs and tappet settings. | 31th May 1933 | Box 162 \ 4 img007 | |
| Order for one dozen modified K.L.G. sparking plugs. | 31th May 1933 | Box 162 \ 4 img008 | |
| Letter to K.L.G. Sparking Plugs Ltd. requesting modifications to the 765A plug. | 31th May 1933 | Box 162 \ 4 img009 | |
| Letter from K.L.G. Sparking Plugs Ltd. regarding the modification and performance of brass fins on a No. 765A plug. | 6th Jun 1933 | Box 162 \ 4 img010 | |
| Letter to a supplier regarding a modification to long reach sparking plugs. | 7th Jun 1933 | Box 162 \ 4 img011 | |
| Letter from K.L.G. Sparking Plugs regarding the supply of six new mica insulated screens for testing. | 8th Jun 1933 | Box 162 \ 4 img012 | |
| Letter from K.L.G. Sparking Plugs Ltd. regarding a modification to an order for the 765-A model. | 8th Jun 1933 | Box 162 \ 4 img013 | |
| Testing K.L.G. screened ignition plugs for tank engines, with results tabulated for performance under different pressures. | 22th Jun 1933 | Box 162 \ 4 img014 | |
| Test report on the water resistance and electrical breakdown of plugs and cables. | 22th Jun 1933 | Box 162 \ 4 img015 | |
| Test report comparing spark plug voltage performance with and without a screen. | 22th Jun 1933 | Box 162 \ 4 img016 | |
| Recommendation to supply a special K.L.G. Co. sparking plug gauge with every Bensport chassis. | 4th Jul 1933 | Box 162 \ 4 img017 | |
| Internal order request for one dozen 14mm X.306 plugs from the Lodge Plug Co. | 30th Aug 1933 | Box 162 \ 4 img018 | |
| Letter to K.L.G. Sparking Plugs Ltd. regarding issues with their plugs during a 10,000-mile test. | 25th Oct 1933 | Box 162 \ 4 img019 | |
| Despatch of three K.L.G. type 765 spark plugs for examination. | 25th Oct 1933 | Box 162 \ 4 img020 | |
| Letter from K.L.G. Sparking Plugs Ltd. regarding the receipt and examination of three plugs. | 30th Oct 1933 | Box 162 \ 4 img021 | |
| Letter to K.L.G. Sparking Plugs regarding spark plug testing and standardisation on a Bentley car. | 16th Nov 1933 | Box 162 \ 4 img022 | |
| Letter from K.L.G. Sparking Plugs discussing the use and modification of aero-type plugs for a Bentley car. | 17th Nov 1933 | Box 162 \ 4 img023 | |
| Letter from K.L.G. Sparking Plugs Limited confirming a works visit for Major Carington. | 4th Dec 1933 | Box 162 \ 4 img024 | |
| Letter from K.L.G. Sparking Plugs regarding the supply and testing of new type 792 plugs for a Bentley car. | 18th Dec 1933 | Box 162 \ 4 img025 | |
| Letter to K.L.G. Sparking Plugs Ltd. regarding poor performance of their aero-type plugs and ordering an alternative for Bentley cars. | 22th Dec 1933 | Box 162 \ 4 img026 | |
| Recommending an order of 50 sets of K.L.G. 765A spark plugs with Stellited points for a Bentley car. | 22th Dec 1933 | Box 162 \ 4 img027 | |
| The correct spark plug gap settings for 14 mm Bentley plugs. | 13th Jan 1934 | Box 162 \ 4 img028 | |
| Decision to discontinue the use of Stellite tipped Bentley sparking plugs in favour of standard nickel manganese. | 13th Jan 1934 | Box 162 \ 4 img029 | |
| Request to K.L.G. Sparking Plugs Ltd. for a hotter grade of spark plugs for a Phantom engine. | 29th Jan 1934 | Box 162 \ 4 img030 | |
| Letter from K.L.G. Sparking Plugs Limited regarding modifications to 765-A and 14 m.m. plugs. | 30th Jan 1934 | Box 162 \ 4 img031 | |
| Letter from the Air Ministry granting provisional airworthiness approval for K.L.G. screening cowls. | 27th Jan 1934 | Box 162 \ 4 img032 | |
| Request to K.L.G. Sparking Plugs Ltd. for a dozen cooler running sparking plugs for a 20/25 HP chassis engine experiment. | 31th Jan 1934 | Box 162 \ 4 img033 | |
| Letter from K.L.G. Sparking Plugs regarding the supply and testing of different spark plugs for a 20/25 chassis. | 2nd Feb 1934 | Box 162 \ 4 img034 | |
| To place an order for K.L.G. spark plugs for Vulture and 20/25 chassis. | 5th Feb 1934 | Box 162 \ 4 img035 | |
| Standardisation of K.L.G. TYPE 765A SPARKING PLUGS. | 15th Jan 1934 | Box 162 \ 4 img036 | |
| Letter regarding the despatch of M.S.V. screens and details of the No. 724 spark plug. | 5th Apr 1934 | Box 162 \ 4 img037 | |
| Unsatisfactory test performance of K.L.G. plugs for a Bentley chassis. | 16th Apr 1934 | Box 162 \ 4 img038 | |
| KLG sparking plugs removed from Bentley Chassis B.57-AE due to engine misfire. | 16th Apr 1934 | Box 162 \ 4 img039 | |
| Examination of plugs for Bentley Chassis No. B.57-AE. | 19th Apr 1934 | Box 162 \ 4 img040 | |
| The electrical testing of K.L.G. plugs for a Bentley chassis. | 19th Apr 1934 | Box 162 \ 4 img041 | |
| Letter regarding the rapid erosion of K.L.G. type 808 sparking plugs during testing on a Phantom II chassis. | 2nd May 1934 | Box 162 \ 4 img042 | |
| Arrangement to send a K.L.G. sparking plug type 808 for examination. | 2nd May 1934 | Box 162 \ 4 img043 | |
| Letter from a spark plug manufacturer regarding the examination and suggested modification of a 765-A plug. | 5th May 1934 | Box 162 \ 4 img044 | |
| Letter from K.L.G. Sparking Plugs regarding the effect of modifying a spark plug's gap capacity and heat resistance. | 5th Apr 1934 | Box 162 \ 4 img045 | |
| Letter to K.L.G. Sparking Plugs Ltd. ordering a set of 12 modified type 765A plugs for a 10,000-mile Bentley car test. | 7th May 1934 | Box 162 \ 4 img046 | |
| Letter from K.L.G. Sparking Plugs regarding the modification and supply of test plugs, assigning the new number 765-D. | 8th May 1934 | Box 162 \ 4 img047 | |
| Letter concerning the excessive point burning on a type 808 sparking plug due to a purposely tapered central electrode. | 8th May 1934 | Box 162 \ 4 img048 | |
| Letter from K.L.G. Sparking Plugs confirming the dispatch of one dozen type 765-D plugs. | 9th May 1934 | Box 162 \ 4 img049 | |
| Invoice from K.L.G. Sparking Plugs, Ltd. to Messrs Rolls-Royce Ltd. | 9th May 1934 | Box 162 \ 4 img050 | |
| Letter from K.L.G. Sparking Plugs regarding a point burning issue with the No. 808 plug on the Phantom engine. | 12th Jun 1934 | Box 162 \ 4 img051 | |
| Selection and modification of plugs for the Bentley car. | 3rd Jun 1933 | Box 162 \ 4 img053 | |
| Request to place an order for K.L.G. sparking plugs and radio screening caps. | 25th Jun 1934 | Box 162 \ 4 img054 | |
| Letter to K.L.G. Sparking Plugs Ltd. requesting a set of 12 aero-type sparking plugs for E.R. Hall's Bentley. | 13th Jul 1934 | Box 162 \ 4 img055 | |
| Letter from K.L.G. Sparking Plugs Limited regarding the despatch of various spark plugs and washers. | 16th Jul 1934 | Box 162 \ 4 img056 | |
| Letter to K.L.G. Sparking Plugs Ltd. regarding an urgent order of plugs for E.R. Hall's Ulster T.T. Bentley race car. | 18th Jul 1934 | Box 162 \ 4 img057 | |
| Letter from K.L.G. Sparking Plugs Limited concerning the dispatch of Bentley Racing Plugs. | 19th Jul 1934 | Box 162 \ 4 img058 | |
| Letter from K.L.G. Sparking Plugs regarding an improved spark plug for the Bentley car. | 1st Aug 1934 | Box 162 \ 4 img059 | |
| Letter to K.L.G. Sparking Plugs Ltd. regarding a modified nut for a standard Bentley spark plug. | 3rd Aug 1934 | Box 162 \ 4 img060 | |
| Letter to K.L.G. Sparking Plugs Ltd. requesting a delivery date for 24 Bentley racing plugs for the Ulster T.T. | 8th Aug 1934 | Box 162 \ 4 img061 | |
| Letter to K.L.G. Sparking Plugs Ltd. detailing test results and criticism of their 836 B model plugs. | 8th Aug 1934 | Box 162 \ 4 img062 | |
| Letter from K.L.G. Sparking Plugs Limited discussing the performance of 836-B plugs and the design of standard Bentley plugs. | 20th Aug 1934 | Box 162 \ 4 img063 | |
| Letter to K.L.G. Sparking Plugs Ltd. expressing satisfaction with their product's performance in a Bentley and approving an advertisement. | 18th Sep 1934 | Box 162 \ 4 img064 | |
| Urgent request for 24 type 827 K.L.G. sparking plugs for testing a special Bentley engine. | 18th Sep 1934 | Box 162 \ 4 img065 | |
| Letter to K.L.G. Sparking Plugs Ltd. regarding the testing of new type 850 spark plugs and Stellited centre pins on a Bentley car. | 15th Oct 1934 | Box 162 \ 4 img066 | |
| Letter from K.L.G. Sparking Plugs regarding the dispatch of experimental plugs for a Bentley engine. | 22th Oct 1934 | Box 162 \ 4 img067 | |
| Letter from K.L.G. Sparking Plugs concerning ignition interference from suppressors on a Philco wireless set in the Duke of Kent's Bentley car. | 9th Nov 1934 | Box 162 \ 4 img068 | |
| Letter to K.L.G. Sparking Plugs regarding testing new type 850 plugs in the Duke of Kent's Bentley. | 9th Nov 1934 | Box 162 \ 4 img069 | |
| Ignition interference and spark plug issues on H.R.H. The Duke of Kent's Bentley. | 10th Nov 1934 | Box 162 \ 4 img070 | |
| Complaint of sooting plugs and radio interference on H.R.H. The Duke of Kent's car, chassis No. B.45.AE. | 13th Nov 1934 | Box 162 \ 4 img071 | |
| The testing of sparking plugs returned from the Kingsbury Service Depot. | 14th Nov 1934 | Box 162 \ 4 img072 | |
| Defective sparking plugs removed from a 3½ Litre Bentley chassis and the subsequent reply from Kingsbury. | 16th Nov 1934 | Box 162 \ 4 img073 | |
| Clarifying the return of a set of sparking plugs for a 3½-Litre Bentley due to potential insulation breakdown. | 15th Nov 1934 | Box 162 \ 4 img074 | |
| Letter from K.L.G. Sparking Plugs Ltd acknowledging a request to convey views to H.R.H. The Duke of Kent. | 16th Nov 1934 | Box 162 \ 4 img075 | |
| Inquiry about spark plugs sooting up on Chassis No. B.45.AE, belonging to the Duke of Kent, potentially due to a fitted wireless set. | 24th Nov 1934 | Box 162 \ 4 img076 | |
| Issue with chassis NO.B.45 AE belonging to the Duke of Kent. | 26th Nov 1934 | Box 162 \ 4 img077 | |
| Letter from K.L.G. Sparking Plugs regarding the welding of Stellite tips to electrodes to prevent point burning. | 26th Nov 1934 | Box 162 \ 4 img078 | |
| Letter from K.L.G. Sparking Plugs Limited regarding the working voltage and design of various spark plugs. | 26th Nov 1934 | Box 162 \ 4 img079 | |
| Letter from K.L.G. Sparking Plugs regarding the despatch of modified type K.1/859 plugs. | 3rd Jan 1935 | Box 162 \ 4 img080 | |
| Letter to K.L.G. Sparking plugs Ltd. requesting a sample batch of 24 Bentley 14mm type 850 plugs with platinum electrodes for testing. | 14th Jan 1935 | Box 162 \ 4 img081 | |
| Internal order for K.L.G. sparking plugs for a Spectre chassis. | 16th Jan 1935 | Box 162 \ 4 img082 | |
| Confirming the handover of 6 K.L.G. 851 plugs for testing in a Bentley test bed engine. | 31th Jan 1935 | Box 162 \ 4 img083 | |
| Order for one dozen K.L.G. type 850 sparking plugs with knurled nut terminals. | 15th Mar 1935 | Box 162 \ 4 img084 | |
| Letter to K.L.G. Sparking Plugs Ltd. regarding an order for one dozen type 850 sparking plugs with specific gap settings. | 1st Apr 1935 | Box 162 \ 4 img085 | |
| Supply of spark plug types 850 and 851 for a 5.B.IV test in France. | 1st Apr 1935 | Box 162 \ 4 img086 | |
| Letter from K.L.G Sparking Plugs Ltd. confirming dispatch of twelve type 850 plugs. | 6th Apr 1935 | Box 162 \ 4 img087 | |
| Letter from K.L.G. Sparking Plugs regarding spark plug gap settings for the 25 HP car. | 11th Apr 1935 | Box 162 \ 4 img088 | |
| Letter to Major Carrington discussing the performance of K.L.G. spark plugs and requesting alternatives for testing. | 24th Apr 1935 | Box 162 \ 4 img089 | |
| Letter to K.L.G. Sparking Plugs Ltd. specifying the gap settings for 'K' type plugs. | 26th Apr 1935 | Box 162 \ 4 img090 | |
| Order for one dozen Bentley K.L.G. type 850 sparking plugs. | 16th May 1935 | Box 162 \ 4 img091 | |
| Letter from K.L.G. Sparking Plugs regarding the dispatch of nine type 744 plugs with stellite electrodes for testing. | 14th May 1935 | Box 162 \ 4 img092 | |
| Order for 24 specific K.L.G. spark plugs. | 30th May 1935 | Box 162 \ 4 img093 | |
| Internal order request for 48 K.L.G. type 893 B sparking plugs. | 3rd Jun 1935 | Box 162 \ 4 img094 | |
| Internal order request for K.L.G. sparking plugs. | 4th Jun 1935 | Box 162 \ 4 img095 | |
| Order for K.L.G. plugs and gasket washers. | 17th Jun 1935 | Box 162 \ 4 img096 | |
| Order for 24 K.L.G.827 sparking plugs. | 19th Jun 1935 | Box 162 \ 4 img097 | |
| Replacing K.L.G. 850 spark plugs with Lodge X.434/2 plugs, which caused audible detonation. | 2nd Jul 1935 | Box 162 \ 4 img098 | |
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