Withdrawn in October 1964 and broken up by Cashmore's: Newport, surely it cannot be on its way there still with its name and numberplates? It was off Cardiff East Docks in 1962 (when Canton closed to steam), was it stored there?

John Dore-Dennis confirms my thoughts "I would suggest that this photograph was taken at Cardiff East Dock Shed. The headland visible in the rear is Penarth Head and the distinctive white building just visible between the grey funnel and the black stovepipe funnel is the Ferry Road public house. The stovepipe funnel belongs to Cardiff Dock's bucket dredger"

4080 "Powderham Castle" seen here was certainly not withdrawn at the date of this image, but like the "Castle" visible behind is stored out of use with her chimney covered to prevent damage to the blast pipe and smokebox interior. Allocated in the 'fifties to Bristol Bath Road this engine was reallocated to Cardiff Canton early in 1960 and thence to Cardiff East Dock in August 1962, but Canton did tend to put engines into storage at about this time, probably having an excess of "Castles" and "Kings" in addition to all fifteen Western Region "Britannias" (which left in September 1961), doubtless too many for their requirements, and I have a reference which confirms that 4080 did go into store in March of 1963 which will probably explain this picture.
4080 is claimed to have achieved the highest mileage for any "Castle", running just under two million miles in revenue earning service before withdrawal came about in August of 1964.