Here are some links to useful sites (in no particular order)

The 16mm Narrow Gauge Modellers Association Association of Shrewsbury Railway Modellers
Accucraft UK Mamod
Roundhouse Engineering Southeastern Railway Museum, USA
Coleham Pumping Station, Shrewsbury Welshpool & Llanfair Light Railway
Bala Lake Railway Threlkdale Quarry and Mining Museum Railway
Ellesmere Model Railway Club Hampton Loade Paddock Railway