Henderson has a long-standing interest in politics. He was a Conservative Party political agent and was the constituency agent for
North Thanet MP,
Roger Gale. Henderson has served as deputy leader of
Swale Borough Council twice and was also a member of
Kent County Council, In the
2005 general election, Henderson contested the
Sittingbourne and Sheppey and came second, losing by only 79 votes to the incumbent
Labour MP
Derek Wyatt. In the
2010 general election, Henderson stood again in Sittingbourne and Sheppey, and was elected as the MP, receiving a 12,383 majority with 50.0% of the vote. Henderson was re-elected at the
2015 general election with a slightly decreased majority of 12,168 and a slightly decreased vote share of 49.5%. He was a supporter of the
Better Off Out campaign which called for the United Kingdom to leave the European Union. In 2010, he had stated that the non-Conservative politician he most admired was
Nigel Farage. In 2014, Henderson responded to speculation about a possible defection to
UKIP by issuing a statement saying defection was something he had considered, but he viewed their other policies as "muddled and contradictory". At the snap
2017 general election, Henderson was again re-elected, increasing his vote share to 60.2% and his majority to 15,211. During the
2019 general election Henderson increased his vote share at the election by over 7% to 67.6% He increased his majority from 15,211 to 24,479. In March 2023, Henderson announced he would retire at the
2024 general election. ==Personal life==