Thanks, Hugo. Nice to see the photos. I made a typo in the previous entry, the all traffic on the line to Denbigh ended was 1968. There were four camping coaches on a siding adjacent to a loading platform (behind the coal truck shown in the middle photo). They were there from 1955 to 1968. BR saw North Wales as an ideal area for the siting of these facilities - in addition to Rhuddlan, there were ones at Glan Conwy, Betws y Coed (a Pullman car!), Aber, Abergele (9 here), and, briefly, at Pont y Pant and Roman Bridge.
I do remember the Marsh Warden but don't recall ever having gone there. You can still see the occasional metal grid in local roads bearing the legend "Rhuddlan Foundry" - mainly road gullies in rural areas.