Built in 1900 to the design of H. Tudor Thornley, the building originally served as the offices of iron importers and ship brokers before being purchased in 1939 by the South American Saint Line Shipping Co. who renamed it Saint Line House. It was later renamed Beynon House before reverting to Saint Line House in 2005.

The Renaissance-style building consists of five storeys plus basement and attic and is five bays wide. The first four storeys of the central bay are stepped forward slightly. The first two storeys are of Bath stone and are rusticated, articulated by banded pilasters. Between the first and second storeys is a series of decorative panels showing the evolution of sailing ships in roundels surrounded by ornate sea monsters and other nautical designs. The entrance in the central bay in through a double door under a segmental fanlight flanked by paired columns with Corinthian capitals supporting two plinths with cartouches. Between these is a panel showing two infants flanking an inscription (now blank). The upper storeys are of red brick with Bath stone dressings. There are swan-neck pediments over the third-storey windows. The third and fourth storeys are articulated by giant fluted pilasters with Corinthian capitals, except for the central bay which is flanked by massive fluted engaged columns with Cornthian capitals and highly decorated bases. These support a dentil cornice. The fifth storey is articulated with square pilasters supporting a parapet with four segmental-headed aedicule's with a central attic under a curved pediment bearing the date `1900?.

(Sources: Cadw Listed Buildings Database; Victorian Society Tour Notes, VS01/16; Newman, Buildings of Wales: Glamorgan (London: 1995), p. 272)
A.N. Coward, RCAHMW, 06.07.2018