Gwili Railway, Carmarthen, West Wales. The Gwili Railway is a living reminder of a Great Western Railway branch line set in the breathtaking Carmarthenshire hills. The trip down memory lane starts at Bronwydd Arms Station, and the steam train follows the route, originally taken by the Carmarthen to Aberystwyth line to a delightful halt at Danycoed. The volunteer run Gwili Steam Railway, is the only steam standard gauge railway operating in South West Wales.