1888 Glyn Valley Tramway "Sir Theodore" 0-4-2. GREAT LITTLE TRAINS OF WALES. 1804 Trevithick's Penydarren 0-4-0 (The World's First Locomotive). PLUS The Big Trains of Wales 1878 North Wales Narrow Gauge Railways (NWNGR) "Snowdon Ranger" 0-6-4T.