Llewellyn joined the Communist Party in 1927 and was first elected as a Communist county councillor to represent the Nantymoel area, near Bridgend, on Glamorgan County Council in April 1932. Although receiving 732 votes, he beat his Labour opponent by only 32 votes. J R Campbell see separate entry, a prominent Party leader had polled well over five thousand votes, over 8%, in the 1931 general election in Ogmore, doubling his 1929 tally.
In 1934, Llewellyn was elected the first Communist councillor on to the Ogmore and Gawr District Council. In 1937, he was re-elected, this time unopposed, to the Glamorgan County Council, again representing Nantymoel.
He was a member of the Ocean Combine Committee, which united 22 pits, and organised miners’ stay down strikes against non-unionism in 1936.
The uncle of Mavis Llewellyn, see separate entry, who also became a Communist councillor, Fred Llewellyn died at the age of 60 in 1940.