The railway was built, we believe, around 1948 (named after then then new-born Prince), and operated by the local council for a while until sold to a private operator, believed to be a Mr Wilkinson, in 1952. The mixture of cars in this postcard is redolent of that period, with some pre-war black ones and a couple of 'modern' types.
The locomotive was sold (does it still exist) was replaced in 1971 by a 'Hymek'-style diesel model, and later by a very ugly internal-combustion locomotive named Dylan, which can be seen along with other views of the line, on a flickr website run by 'trainsandstuff.' The great changes of the 1980s, as the new A55 road was driven through the town and the shopping centre was built on the railway goods yards site, also saw the end of the railway, which (we believe) closed in 1987. Special thanks to David Lloyd and George Jones for help with this item.
Colwyn Bay has seen at least three other miniature railways. One apparently ran in Eirias Park around 1970, and another, portable, system, known as the 'Narrower Gauge Railway' - built by a Richard Morris - was installed in the same Park in 1991, and ran for a few years.
http://www.nwrail.org.uk/nw1112c.htm