The Wrenn brothers decided to design their new Formula 152 system to be the most realistic and to recreate full size motor racing as much as possible. The system was to have the ability to race more than two Cars at a time, be able to overtake and also have the ability to tune the Cars. What was remarkable about this venture was the fact that the Cars were to be produced in the unusual and very small scale of 1/52 and at that time no manufacturer had an existing electric motor small enough to fit into these tiny Cars. So literally the Wrenn designers started with the proverbial ‘blank sheet of paper’ and produced a Vibrator motor which could run on either an AC or DC electrical supply.

It was envisaged right from the outset that the Wrenn Formula 152 system would include many innovations, the unique one being the independent control of up to three Cars on either lane, hence the title ‘Triple Electric Model Motor Racing’. This revolutionary system was made possible by having two conductor rails on either side of the slot in the Track and the Collectors underneath the Cars having the facility of being adjusted to pick up from either of two positions. Cars could then be set to pick up from the two outer rails, the two inner rails or one inner and one outer rail.

A special Deflector Straight was introduced to enhance the facility of being able to race three Cars on each lane and it provided a unique way of moving a Car from one lane to the other for overtaking. The small size of the system meant that quite interesting layouts could be assembled on the proverbial dining room table and even simple layouts could create more interest with this overtaking facility.

After two years of extensive research and testing, Wrenn issued their first promotional leaflet titled ‘Sensational New Winner’ in 1959 to introduce their new system and then Wrenn Formula 152 was finally ready to release to the public.

The very first official appearance of Wrenn Formula 152 was at the 1960 Brighton Toy Fair where it was described as the ‘sensation of the show’. After this very successful launch, the new Wrenn Formula 152 was eventually made available for the public to purchase later that year, in time for Christmas. The first item that was made available was the No 1 Basic Set which was released at the end of September. Additional items such as the individual Cars, Track sections, Controllers, Return Leads, the Bottle of Oil and the Instruction Manual were made available from mid-October 1960 onwards. At this same time the first Service Spares which included the Contacts, Collectors and Tyres were also being made available.

Very favourable reviews were appearing in the modelling press at this time and an initial ‘first impression’ review was featured in the very first issue of the newly renamed ‘Model Maker and Model Cars’ magazine in February 1961. This was followed by an in depth review in the later July 1961 issue, which devoted over three full pages to a comprehensive appraisal of the Wrenn Formula 152 system together with an evaluation of it’s Vibrator motor. This review article had been purposely delayed until the Deflector Straight had been launched and tested in conjunction with the magazine’s staff members and their previously supplied Basic Set.

All of the range of Wrenn Cars were Grand Prix Cars from the late 50’s and early 60’s and the first two Cars produced were the Red Ferrari 256 and the Dark Green Cooper T51. They featured Vibrator motors and this type of motor would also be used later by other slot car manufacturers such as Meccano with their Circuit 24 range but especially in HO, initially by Playcraft and then Aurora. The Cars themselves had two-piece injection-moulded nylon bodies, comprising a Chassis, which retained all of the internal components such as the Motor, Axles etc, and a Body Top with a clear polystyrene Windscreen, a nylon Driver and they ran on die-cast white metal, spoke-effect Wheels with rubber Tyres. The first two Car types also featured Exhausts manufactured from die-cast white metal, however all of the later Cars had these manufactured from injection-moulded Silver-Grey polystyrene.

Each Car included a Speed Control Lever underneath the Chassis, so that their maximum speed could be pre-set. This provided the facility of either limiting the Car’s top speed for young children to become skilled at controlling the Cars or to provide a Car for the individual to race against with a pre-set speed. This was another ‘first’ that Wrenn introduced which would surface many years later in other manufacturer’s products, and in some cases, would last until the 1980’s. The Instruction Manual stated that the Speed Control Lever could either allow higher maximum speeds with slower acceleration for large circuits or faster acceleration with a lower maximum speed for small, tight circuits. 

Wrenn started to expand their range of Cars and in the following year they introduced the Yellow Ferrari and the Blue Cooper. This would set the trend of having two different colours available for each type of Car and would apply to all future launches. The initial range of Car types was then expanded with two additional Cars this time with a late version of a Maserati 250F which was available in Red or Blue and a Vanwall which was available in Light Green or Yellow.

To align with the launch of the August 1961 Price List, a range of four new Sets were announced. Two of them contained two Cars whilst the other two were larger Sets and these contained three Cars. Two Extension Packs were also announced at the same time, to enable the original Set to be enlarged with extra Track sections and one of them also included an extra Car and Controller. A range of Accessories was introduced and these were added to over the years to enhance the slot racing experience. These included different pieces of Track, Buildings, Figures, Fencing, Flags and Flag Poles.

In order to promote the Wrenn Formula 152 range a number of fully working and landscaped track layouts were assembled which were mounted onto scenic boards as self-contained units. They included items such as the racing Buildings and the Landscape Sheets and some of them even included railway items from the Wrenn range of permanent way trackwork. These layouts were taken to Toy Fairs and Exhibitions and photographs of them were used in the Instruction Manual and also on the rear cover of the Catalogues to promote the total Wrenn Formula 152 experience. Wrenn decided to make an offer of supplying one of the smaller landscaped layouts to dealers in the trade to assist with advertising Wrenn Formula 152 to the potential buying public.

By 1964 the Wrenn designers had been working to improve Formula 152 and the decision was taken to introduce another custom-built motor, this time purely DC, but it was again certainly not conventional. There was a period when both types of motored Cars were available and all of the previous Vibrator-motored Cars were then also made available powered with this new rotary DC motor. New Mk 2 Controllers were introduced to accompany the DC motors and these now featured a variable resistance rheostat replacing the earlier AC version which, like many other manufacturers of that time such as Scalextric, VIP and SRM, had originally just been basic on/off switches. Both versions of the Controllers featured a separate slider to lock the control button. When this was used on the original Mk 1 version of the Controller and, in conjunction with the Speed Control Lever underneath the car, this gave the Vibrator-motored cars their pre-set speed.

From their model railway experience Wrenn were well aware of the enormous potential for expanding sales with trade overseas and negotiations took place with various companies to act as distributors within other countries. During the period 1963/4, which was when Wrenn Formula 152 was probably at it’s maximum popularity and global coverage, Wrenn stated that ‘Formula 152 Motor Racing was already popular in 40 countries’ obviously making it truly international!

Eventually the Vibrator-motored Cars were discontinued and removed from the Price List but the Service Spares for them were still available from the factory. Wrenn continued to service these cars until it was deemed uneconomical to continue. In these situations Wrenn honoured the warranty and supplied new replacement DC-motored cars. The range of Cars was then finally expanded with the addition of two more Cars, this time a BRM P578 available in Blue or Light Green and a Porsche 804 in Red or Yellow. These completed the Wrenn Formula 152 range of different Car types, with these last two Car types only being available with the DC motor.

Looking at the slot car modelling press of the time it was becoming increasingly noticeable that the larger dealers were not stocking Wrenn Formula 152 Sets any more. Whether their popularity had just been diminishing coupled with increased competition, which was cheaper to buy, all seemed to contribute to the eroding of Wrenn’s position in the market place. These factors may have prompted some of the later, significant decisions within the company.

At the end of 1966 Wrenn decided to change its marketing strategy by offering three very different Special Sets. These included everything that was needed to assemble a fully working layout with all of the Accessories such as a Lap Counter, Track Pits and Grandstand Buildings, Flags and Flag Poles, Track Personnel and Spectator Figures that had previously been available separately up until that time. These Sets were all advertised to be sold at almost half price so they were priced to be very competitive. However it is interesting to note that documentation has been discovered showing that Wrenn were still exporting Formula 152 Cars and Spares to five countries across Europe up to March 1967, and possibly even later than that.

During 1967 Wrenn decided to introduce a new range called ‘Grand Prix’ slot racing with a third type of motor. These Cars were intended to run off a 9-Volt battery supply, they were much cheaper to produce than the previous versions and, in fact, this introduction of a cheaper range had initially been suggested back in early 1962. As the decision to introduce this new range was more than likely a political one, as yet, there isn’t enough information available to fully comment. Various rumours do exist regarding the Lines Brothers buy-out of Wrenn and the implications to the future manufacture of Formula 152 with Lines Brothers already having their Scalextric range, but nothing has been confirmed.

Only one Set, the ‘Flying Figure-8’, was produced in this final range which included two Cars and Controllers, there were Track sections and Bridge Supports to assemble a small figure-of-eight layout, Fencing and Fence Posts, two unpainted 1/52 scale Figures from their range and the obligatory Bottle of Oil. Apart from the two Cars, the majority of the other components in the Set were assembled from Wrenn’s Formula 152 range. The Controllers in the Set were the original Mk 1 type, featuring just the on/off button, and the Cars were produced more economically this time. They had Pale Grey injection moulded Exhausts and they only had number roundel transfers applied with no Silver painting for the highlighted details, as of the previous Cars. These Cars even had oversize Collectors, which were pieces of braid the same size as those used on 1/32 cars, replacing the normal custom-made brushes. This was obviously a conscious decision and meant that the braids swept over both sets of the track pick-up strips so that multi-car running in each lane had to be forsaken and obviously also lane changing. Apart from the Set a list of additional Cars, Track and Accessories that were available was printed and issued in each of the Sets stating that all of these items were now only available direct from the manufacturer.

This final attempt was the last death-throw of a company that had less than ten years earlier established itself at the forefront as a serious and possibly the most ingenious slot car manufacturer. Over the years, especially during their early period, the company took it’s initial innovative product, continually invested in developing it further and adding to the range of Accessories but unfortunately this all ultimately ceased just after the mid 60’s leaving a wonderful legacy. However the company did not end there but Wrenn significantly expanded their production of items in the model railway field to include locomotives and rolling stock, going on to have many more successful years of existence.