He left Firestone’s in early 1958 to join as manager of the Luton based ‘Sporting Motorists Agency’, a trade name for ‘Dante’ tuning parts for Austin 7’s. With ‘Dante’ not in the best of health—it folded shortly afterwards, he set up his own similar company, ‘SPEEDEX Castings and Accessories Ltd’, in an old hat factory at 33 Jubilee Street of Luton. His time at Dante obviously had familiarised him with their suppliers as his company’s products were of a similar range and bore a striking similarity to his competitors – they were from the same Horston Foundry of Dan Taylor in Derbyshire. The first SPEEDEX advert appearing in May 1958.

Jem was an active member of the 750 MC, he had been building his own Austin 7 special and successfully raced it in the 750 MC Formula, winning the ‘Goodacre’ Championship at the end of 1959. This low sleek special made from a frame welded from electrical conduit skinned in aluminium formed the basis of a design produced by his company – the ‘750’.  Up to 200 were sold through 1959 to 1961 for £49 in both short and long wheel base forms to suit both types of donor Austin Sevens. For the 1960 racing season and onwards the ‘Jem Marsh Trophy’ was presented to the best turned out car, based on the scrutineer’s opinion, that had competed in five or more 750 Formula races encouraging quality and presentation.

With new affordable sports cars not easily available in the late 50’s – most British production was for exporting and the current purchase tax could be as high as a discouraging 40%, special building became the only way for young enthusiasts to economically get an interesting car to their own requirements. Austin Sevens were both readily available and easily tuned to give a respectable turn of performance. Being simple and easy to work on they formed the ideal basis for a ‘special’. As a consequence the demand for special tuning parts grew and business’s such as SPEEDEX could rapidly expand to supply it. SPEEDEX developed a range of parts along similar lines to his competitors including engine, suspension and body parts. Perhaps the most striking and innovative being 15” aluminium wheels.

Jem in his successful 750 during the 1959 racing season

To complement his own ‘750’ model, SPEEDEX put into production as the ‘Silverstone’, the fibreglass body shell successfully developed and raced by Mike Featherstonhaugh’s Team Sigma. Up to 40 ‘Silverstone’s’ were made from these moulds some by Cambridge after the demise of Speedex, see the ‘Adverts’ page. Initial price was £70 falling to £55 in an attempt to stimulate sales. With increasing demand more premises were found, 17a Windsor Street in Luton which after an overlap with Jubilee Street became the companies base. Another business outlet was the sale of SPEEDEX bodies and parts through other retailers around the country.

Diversification into Ford based specials was around the development of the ‘Sirocco’ design by Peter Hammond, a fibreglass shelled coupe on a Ford or specially designed space frame ‘Mercury’ chassis inspired by the Maserati ‘bird cage’. Initially designed with gull wing doors to compensate for high sills, later shells reverted to conventional front hinged doors. Despite the optimistic claims in the company adverts only approximately 20 of these shells were made through 1960 and ’61 at £99 each. To complement this model and to appeal to a different range of customers some special parts, notably aluminium cylinder heads were produced for the Ford based specials.

Around this time a ‘Spree-Kart’ go cart with a range of options and accessories was also advertised by the company. Taking a lead from the A7 wheels, cast aluminium go cart wheels were made, with wheelbarrow tyres—the only suitable size then available!

 

The advent of the  relatively cheap and available Austin Healey Sprite and Mini along with a reduction in purchase tax in 1959 brought about a decline in specials building. Advances in engine design made the A7 and Ford specials based on old side valve engines comparatively slow — all of which eventually then lead to SPEEDEX folding. Adverts ceased in December 1961 and soon after Cambridge, another of the A7 tuning companies were offering SPEEDEX parts in their adverts.

 

Jem moved to work with Leslie Ballamy’s LMB company before the Marcos venture really took off. The SPEEDEX name was briefly revived by Jem in the 1980’s as a car parts supplier before being sold to a competitor. Jem is still actively involved in the sports car business.

 

For related stories (and acknowledgement of the bits of stories I’ve ‘borrowed’) see;

· 1950’s specials web site

· May 2003 article in Classic and Sports Car magazine

· Total Sportscars web site (see ‘Links’ page)

· The book ‘MARCOS, story of a Great British Sportscar’ by David Barber has a SPEEDEX chapter and other information relating to Jem’s early career before Marcos.

· The Association of Austin Seven Clubs magazine 1994D edition has a short SPEEDEX history.

A chance encounter with ex De Havilland designer Frank Costin, who apart from aircraft design, had worked on the Vanwall and Knobbly Lister Jaguar led to the opening of a new branch of the firm, the Monocoque Body Chassis Company. Together they produced the first Marcos GT car  with a novel plywood structure in late 1961. They were joined by the other synonymous Marcos designers Dennis and Peter Adams in 1960.