Fishguard County Secondary School opened in 1954 (officially opened in 1955) as the first bilateral school in Pembrokeshire. In doing so, it replaced the former grammar school that was built in 1897. It was originally designed for 330 grammar school pupils with a future secondary modern school for 450, but it opened as a combined grammar and secondary modern school. The school was built at a cost of over £250,000 by Gibson and King, Milford Haven, to the designs of County Architect Lt. Col Walter Barrett in modernist style, with brick, stone, and concrete construction with flat roofs and bands of glazing. The premises, including the playing fields, covered an area over 20 acres, with part of the hillside being levelled as part of the construction. At the south end, classrooms were set off at an angle of 60 degrees for the purpose of maximising sunlight; large windows stretched from the ceiling down to low sill height. 

The two-storey school consisted of 18 classrooms, two art and craft rooms, four laboratories, two domestic science rooms, two general practical rooms, a library, an assembly hall with seating for 900 and made available for community use, gymnasium with separate boys and girls changing rooms, metal-work room, woodwork room, staff rooms, cloakrooms, conveniences and tarmac playgrounds.

Presently Ysgol Bro Gwaun, the comprehensive school educates approximately 525 pupils between the ages of eleven and sixteen. On 14th December 2015, plans by Pembrokeshire County Council and the architects Stride Treglown for a £10.5 million extension to the school went on public display; one of many school construction projects across the country facilitated by Welsh Government's 21st Century Schools Programme. This extension took the form of a 'brand new three storey teaching block,' which was to 'include the creation of a Learning Resource centre,' 'provision for bilingual Special Education Needs' and 'new community learning facilities.' The plans for the teaching block were 'part of an overall investment of £14.7 million in Ysgol Bro Gwaun which includes demolition of most of the current school building and new sports facilities,' although 'the school's existing hall and gymnasium were to be retained, along with the design technology block, which is only about 10 years old.' The contractors on the 5,000 square metre teaching block were BAM Construction Limited. In May 2018 the new teaching block was officially opened by the then Cabinet secretary for education, Kirsty Williams AM.

M. Ryder, RCAHMW, 30th January 2019. Updated by M. Powel, RCAHMW. December 2023.

Sources: www.westerntelegraph.co.uk article entitled 'Fishguard to get £10.5 million to build modern school,' 24th December 2015; www.pembrokeshiresbestmagazine.com article entitled 'Fishguard: Ceremony held for Ysgol Bro Gwaun extension,' 17th March 2017; www.countyecho.co.uk article entitled '£10.9m school extension officially opened' 8th May 2018; 'Demolition of Ysgol Bro Gwaun Comprehensive School, Fishguard', Walters Group Website.; 'Fishguard's new school has commanding view of bay', Western Mail, 9 September 1954, p.7.