Other Garden Railway Scales
See also: Garden Railway Links, Suppliers and Ride On
Big Scale, Small Space?

There's a lot more information on this Gn15 website.
For those interested in constructing "Micro Layouts", there are examples and plans available from Carendt.com
Scale: ~1:20th
Gauge: 18mm (representing 15")
Even narrower gauge track

Scale: ~1:20th
Gauge: 9mm (representing 7")
Gauge 1 in the garden. Large scale, large space

See in particular the article on baseboard construction and the gallery for the photos.
There's a subtle difference between British "Gauge 1", which is a scale of 10mm to the foot (1:30.5 scale), and International "Gauge 1" which is a scale of 1:32. There's a detailed explanation here.
(N.B. some links don't work in Firefox because of the use of '\' instead of '/' in the addresses. If this causes you problems, try here for the baseboard pictures if you're having trouble)
Scale: ~1:30.5
Gauge: 1¾inch, 44.45mm (representing 4'8¼")
Common name: Gauge 1