Born at Wells-next-the-Sea, Norfolk on 24 August 1900, the son of a smallholder, he was educated at Wells Elementary School and left at the age of thirteen to work on the land. At sixteen, he joined the National Union of Agricultural Workers and at nineteen became secretary of its Wells branch. As a winner of the Buxton Memorial Scholarship he attended Ruskin College, Oxford where he took a diploma in economics and political science. He then went on to the International People's College in Elsinore, Denmark.
He was placed on the Swaffham Primitive Methodist Circuit plan as a local preacher in 1920 while living at Sporle.
His interest in politics led to his being appointed Labour Agent in Dover in 1924. Two years later he became the Labour Agent in Cambridgeshire. He was elected to Norfolk County Council in 1934, then to Swaffham Rural District Council the next year when he also unsuccessfully contested the South-West Norfolk constituency. However in 1945 he won the seat by a very small majority. At the 1950 election he was once again elected by a very small margin. In the election in the following year he was defeated, but regained the seat in 1955 - the only Labour gain in an election which resulted in a Conservative victory.
On several occasions he appeared on radio and television to answer audiences' questions. He was appointed a JP in 1934. The questions he asked in Parliament usually concerned farming matters and he was appointed a member of various Parliamentary delegations. He continued to work on the land as a farmer up until his death. He belonged to the NUAW and NFU – one of very few people a member of both unions.
In 1957 a residential home for the elderly at King's Lynn was named 'Sidney Dye House' as a tribute to his work for the Welfare Committee of Norfolk County Council. For many years he led the labour group on Norfolk County Council.
His home near Swaffham was close to the proposed airbase site at North Pickenham for intermediate range nuclear missiles. Protesters gathered and Dye visited the site in December 1958 to join the campaign there. The next day he asked questions in the House of Commons and made statements regarding the behaviour of police and protesters.
The following morning, 9 December 1958, he was killed near Swaffham in a head-on crash with another vehicle as he travelled to Brandon Station to return to London for a parliamentary committee meeting on the Small Farmers' Bill. The subsequent inquest noted that early rain had been followed by frost, making the road surface treacherous and that there were dazzling effects from a low sun. The car had skidded on the slippery road. The Coroner recorded a verdict of accidental death
On the day of his funeral four hundred people packed Swaffham Methodist chapel for the funeral service, many of them in tears. A silent throng of more two thousand people lined the streets and the route to Sporle village where the internment took place to pay their respects to a much-loved figure.