https://www.scalefour.org/

The Scalefour Society

Quote from their website:-

The Scalefour Society caters for the needs of railway modellers working to the scale of 4mm/ft (1:76.2), the most popular of the British model railway scales. It promotes and encourages the use of effective modelling techniques and fine scale standards among all 4mm railway modellers with a particular emphasis on the use of scale wheels and track.