Heycock was born in Margam and began his career as an engine driver with the Great Western Railway.
He subsequently rose to a powerful position in South Wales local politics through his trade union connections and membership of the Labour Party, a "personality of transcendent authority".
He was first elected to Glamorgan County Council in 1937 at a by-election following the re-election of long-serving miners' agent John Thomas of Pontrhydyfen as an alderman.
Heycock was chosen as Labour candidate at the expense of Joe Brown, a former mayor of Port Talbot and a close associate of Ramsay Macdonald when he was MP for Aberavon.
[3] In 1973 he was elected unopposed as councillor for Margam Central on the new West Glamorgan County Council.