That's a rare bird, thanks for sharing.
In Laurence Dunn's 'Ships of the Union-Castle Line' she is shown prewar with a black hull which suggests general cargo rather than reefer. There seems to have been a period between the end of WW2 and 1954 when the general cargo ships were favoured with a lavender hull.
Built by Short Bros Sunderland, in 1921 or 2 along with sister ship Sandgate Castle. Gross tonnage 7607t, scrapped UK 1950.
Sandgate Castle lost to fire of Cape Hatteras in June 1937, bound New York to Cape Town.