John was selected to contest the Basildon seat in 1997, but was beaten by the Labour candidate, Angela Smith. He was selected for the neighbouring seat of Billericay and District for the 2001 election, which he re-took for the Conservatives with a majority of 5,013. He gave his maiden speech on 20th July.

In the 2001 Conservative leadership contest, John supported David Davis.

From November 2001 to December 2002, John was a member of the Education & Skills Select Committee. In June 2002, John was appointed a Shadow Health Minister, taking on the cancer portfolio amongst others. However, he resigned as a Shadow Minister on 18th March 2001 in order to vote against the Iraq War.

By July 2003 he was back in post as a Shadow Health Minister, moving to the Opposition Whips Office in July 2007 where he served until the 2010 General Election.

In the General Election on 5th May 2005, John was returned as the Member for Billericay with an increased majority of 11,206, winning 52% of the vote. His Labour opponent was Anneliese Dodds, now the Labour MP for Oxford East.

In the 2005 Conservative leadership contest, John once again supported David Davis.

In the 2010 General Election on 6th May 2010, John was returned for the newly-formed seat of Basildon & Billericay with an increased majority of 12,398, winning nearly 53% of the vote.

In July 2010, John was elected as a member of the Foreign Affairs Select Committee, on which he served until May 2017.

On 21st March 2011, John was the only Conservative, and among only 15 MPs, to vote against military intervention against Libya.

In October 2011, John participated in a debate secured by David Nuttall MP which called for a referendum on Britain’s EU membership. Whilst the vote was lost by 483 votes to 111, over 80 Conservatives voted for it. More details are on the Brexit page.

In February 2012, John secured a debate calling for the use of military action against Iran to be ‘taken off the table’, following the publication of a report from the International Atomic Energy Agency. The vote on his motion was lost by 285 votes to 6.

In March 2012, John and the British Nuclear Test Veterans’ Association (BNTVA) launched their campaign for official recognition and support for nuclear veterans and their families. The former was granted by David Cameron as Prime Minister in June 2014, and the latter was addressed by the formation of the Aged Veterans Fund in Budget 2015. More details are available on the test veterans’ page.

In June and November 2012, John organised two letters from Conservative back benchers to the Prime Minister, calling for him to introduce legislation to provide for an EU referendum after the 2015 General Election. He also founded the All-Party Parliamentary Group for an EU Referendum in October 2012.

In October 2012, John secured a debate opposing the abolition of the 2nd Battalion, The Royal Regiment of Fusiliers, which was being cut as part of the Coalition’s defence reforms. On the day of the debate, John helped organise a march of Fusilier veterans on Parliament, thought to be the first time (ex-) soldiers had marched on Parliament since Cromwell.

Also in October 2012, Ofgem passed its Energy Market Review, which incorporated some of the conclusions John had come to as chair of the Billing Stakeholder Group. More details are on the Energy Tariffs page.

In May 2013, following David Cameron’s ‘Bloomberg Speech’ in which he offered an in/out EU referendum after the 2015 General Election, John organised a further letter of Conservative backbenchers calling for the referendum legislation to be included in the Queen’s Speech. When it was not included, John tabled an amendment to the Queen’s Speech expressing regret that the legislation was not included – the first time since 1940s that a Government backbencher tried to amend the Queen’s Speech. Though defeated in the subsequent vote, over 100 Conservatives supported John’s amendment. More details are on the Brexit page.

Throughout 2013 John raised his opposition to the Government playing an active role in the Syrian Civil War, and was concerned that the Government might start sending lethal support. Through his back bench debate in July 2013, John and other backbenchers extracted the promise from the Government that it would ask Parliament’s permission in a vote before sending arms to Syria.

In August 2013, John took an active role in opposing military action against the Syrian Government (more details are on the Syria page). For these actions and for his amendment to the Queen’s Speech, John was chosen as one of the BBC’s Parliamentarians of the Year for 2013/2014.

In November 2013, John attempted to amend the Defence Reform Act to pause the implementation of the Coalition Government’s policy of replacing 20,000 Regulars with 30,000 Reservists. His amendment was narrowly defeated by 306 votes to 252.

In September 2015, John and other Conservative MPs successfully opposed the Government’s decision to suspend the usual purdah rules before the EU referendum. This would have allowed the Government’s press officers to work during the referendum, potentially outgunning the campaign to leave the EU in the referendum the following year.

In the General Election on 7th May 2015, John increased his majority in Basildon & Billericay to 12,482, winning over 50% of the vote.

In December 2015, John tabled an amendment to the Government’s motion to broaden the military action against Daesh to Syria, and voted against further strikes.

Having waited to learn the outcome of David Cameron’s renegotiation with the EU, in February 2016 John came out in full support of leaving the EU. After the result, John was one of the first to ask for the rights of EU citizens living in the UK to be guaranteed.

In July 2016, Sir John Chilcot presented his inquiry on the decision to go to war in Iraq in 2003, to which John had made submissions and been interviewed by Sir John. John felt vindicated that Sir John came to the conclusion, as he had in 2003, that war was not the last resort at the time that Tony Blair ordered the invasion of Iraq.

In the General Election on 7th June 2017, John increased his majority in Basildon & Billericay to 13,400, rising along with Conservative results across Essex. John was supportive of Theresa May continuing as Prime Minister, and supported the agreement with the Democratic Unionist Party.

In the 2017-2019 Parliament, John consistently supported leaving both the Customs Union and the Single Market, in order to fully respect the outcome of the EU referendum. In January 2019, he tabled an amendment to approve the Withdrawal Agreement as long as the UK was able to unilaterally terminate the Northern Ireland protocol. The amendment was defeated by 600 votes to 24 – believed to be the largest Parliamentary defeat in history.

In the 2019 General Election, John increased his majority in Basildon & Billericay to 20,412, winning nearly 70% of the vote. He voted for the Withdrawal Agreement, which paved the way for the UK to leave the EU at the end of January 2020.

When the pandemic struck in March 2020, John supported the Government’s measures to protect the public from the virus, though in the autumn of 2020 John tabled amendments to allow MPs whose family members were clinically extremely vulnerable to contribute virtually, but was unsuccessful. In December 2021, John voted against so-called ‘vaccine passports’, given that the experience of using them in the other nations of the UK had no discernible effect.

During the pandemic, as chair of the British Council All-Party Parliamentary Group, John campaigned successfully for a large package of financial support to keep the organisation going as the commercial activities it relies upon stopped worldwide. Unfortunately a shortfall in this support meant the closure of 20 of the British Council’s overseas offices, but a better-than-feared outcome in the 2022 Spending Review meant that two offices (Australia and New Zealand) could be re-opened and no further overseas closures were necessary.

In November 2021, John tabled an amendment to the Health & Care Bill to encourage the NHS to focus more on outcomes when it comes to cancer treatment. The amendment was supported by nearly 70 MPs across the Commons and widely in the Lords, and was also endorsed by the former Chief Executive of Cancer Research UK. The Government accepted the amendment, which is now Clause 5 of the Health & Care Act.

Also in November 2021, John did not vote in support of the Government’s motion on Owen Paterson, believing that the Commons should have endorsed the Committee on Standards report in the usual way.

Having kept an open mind during the ‘Partygate’ scandal, in May 2022 John withdrew this support from Prime Minister Boris Johnson following the publication of the Sue Gray and Metropolitan Police reports. In his opinion, the scale of the rule-breaking uncovered by these reports made several statements the Prime Minister had made in the Commons impossible to believe.

Having supported Penny Mordaunt until she was eliminated from the contest, John then supported Rishi Sunak in the summer leadership contest. He supported him again following the resignation of Liz Truss.

In December 2022, John became a member of the Treasury Select Committee.

In June 2023 His Majesty the King appointed John a Commander of the Most Excellent Order of the British Empire in his birthday honours, for his public and political service