He went to Welholme Primary School on Heneage Road, then Wintringham School on Weelsby Avenue in Grimsby. He was a councillor for Ashby in Scunthorpe on the former Humberside County Council from 1989 until 1996. He stood in the 1992 election for the seat of Brigg & Cleethorpes. From 1996–7, he was leader of North Lincolnshire Council and was the Chair of the Humberside Police Authority from 1993–97. From 1977 until 1987 he worked in computing for Imperial Foods (now known as Young's Bluecrest) in Grimsby and Seven Seas Health Care (owned by Merck KGaA) on Hedon Road in Hull. He married Linda Mary Kirman in July 1987. They have two daughters Hannah, born January 1988 and Lydia, March 1997 also a son, Jacob born May 1993 and reside in Winterton.
He was first elected at the 1997 election, and was seen as a strong supporter of Tony Blair and New Labour.
He served on the Home Affairs Select Committee, the Universities, Innovation, Science & Skills Select Committee and the Science & Technology Select Committee.
He Chaired the Associate Parliamentary group for Animal Welfare and was twice voted by MPs and Peers of all parties as the Dods Charity Champion for Animal Welfare.
He served as Parliamentary Private Secretary (PPS) to Lord Williams of Mostyn from 2001 to 2002. He then became PPS to David Miliband at the Department for Education and Skills and then the Cabinet Office. After the 2005 general election he was made a Government whip.
On taking office Gordon Brown appointed Cawsey to be a Vice-Chair of the Labour Party with responsibility for animal welfare.
He is a musician and has performed in local bands such as Mandrake, Sneaky Feet, Brix & Chinese Whispers and he sings and plays bass guitar in the rock group MP4, which is composed of four MPs, Cawsey, Peter Wishart MP, Greg Knight MP and Kevin Brennan MP.
He played from 1990–97 in a well known local 60s covers band, The Moggies, the band reformed in 2011 and have established a popular local following once more.
In late 1997 he had cancer which he has now overcome.
He qualified as a football referee in 2010 and officiates most weekends.
Since leaving parliament he has worked for the World Society for the Protection of Animals, firstly on their successful UK campaign to stop a large mega-dairy being built in Nocton, Lincolnshire, he was briefly their Chief of Staff running the Office of the Chief Executive before being promoted to be their Director of Policy & External Affairs in 2012.
He is a Winterton Town Councillor and an after dinner speaker.
He was many people's favourite to beat John Prescott to be Labour's candidate in the Police & Crime Commissioner Election in 2012 but withdrew from the race to take up his new position with the World Society for the Protection of Animals.
He is the Secretary of the Jerry Green Dog Rescue Trust and a member of the Winterton & District Lions (President 2011–2013).