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History of the Group


The ScaleSeven Group has its roots in the 1970s. Ken Cottle and some others had been dissatisfied with the compromises of ‘finescale’ 32mm Gauge O and, much as the ProtoFour and ScaleFour members had done for 4mm scale modelling in the late 1960s, decided to work on a set of workable standards for true 7mm scale modelling. The standards were based around the correct rail and wheel profiles, with a back-to-back distance of 31.2mm and a rail gauge of 33mm.

Why 33mm gauge?

The logic behind the gauge of 33mm is sound. In the dim and distant past of model railways, the HO standard of 16.5mm gauge stood for Half O. Multiply by 2 and you get 33. Standard finescale Gauge O is 32mm gauge, which is a metricated corruption of the original 1-1/4 inch Gauge O. In its original form, with massively wide wheels and deep flanges, Gauge O used the equivalent of 33mm gauge. As standards were ‘fined down’, the track was narrowed to match the wheelsets.

The Group is formed

The ScaleSeven Group was formally established in May 1989, and became a specialist group under the banner of the Gauge O Guild. The Group still has an independent financial base, and membership of the Group does not mean membership of the Guild, or vice versa.


The Group’s aim is to promote accurate and true 7mm scale modelling. This has been perceived by some critics to mean the Group is elitist, although nothing could be further from the truth. The Group’s counter to the criticism is that if a modeller can produce an accurate scale model to finescale Gauge O, then they can also produce an accurate scale model to S7. The standards have been proved to work time and again so, in effect, a newcomer to the 7mm scale should not need to consider working to an incorrect gauge of 32mm and can move straight to 33mm ScaleSeven. Many of the 7mm kit manufacturers now design their kits to allow for S7 clearances, and most wagon kits only need a ScaleSeven wheelset to complete the conversion. It’s that simple!

A holistic approach

The Group is keen, however, to steer away from the notion that it’s all about the track and wheel standards. It is preferred to consider modelling to S7 as a state of mind—the modeller should aim to build everything to the same standard, be it locos, wagons, carriages, signals, trackwork, lineside structures, road vehicles, plants and animals, people. This holistic approach can provide for some staggeringly beautiful models. Reproduced in this web site are some examples of modelling to the ScaleSeven standards, and the photos alone are testament to the correct ‘look and feel’, made possible by matching correct wheel profiles and trackwork to skilled modelmaking. Follow this link to our Showcase section.

It has taken some time for the S7 standard to be widely recognised. Group membership is currently in three figures worldwide. ScaleSeven layouts which have been or are currently on the UK circuit are Bob Essery’sDewsbury, Ken Cottle’s Weston Green, Geoff Stenner’s Oakhurst, Peter Kibble’s Little Severn Mill, Julian Russell’s Wyebridge High Street, Simon Thompson’s Braunston Gate, and Ian Middleditch’s Auchlin, to name but a few.

If your finescale interests lie in other scales, please visit our External Links page.

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