Early parliamentary career: 2005–2012

At the 2005 general election, Walker was elected as Member of Parliament for Broxbourne.^[7] Notably, given his subsequent criticisms of the government led by Liz Truss (see "Retirement", below), in the Conservative Party's initial prospective candidate selection process Walker defeated the future prime minister, who had also made the party's shortlist for the Broxbourne seat.^[8] Upon election, he sat on the Scottish Select Committee from 2005 to 2010 and was also a member of the Public Administration Select Committee from 2007 to 2010. He is currently a member of the House of Commons Privileges Committee.^[9]

Walker was one of the 23 MPs to sign the motion of no confidence in Speaker Michael Martin.^[10]

In 2011, Walker made what is believed by some to be the shortest Parliamentary speech in history, when he made a four-word contribution in a European Union debate on membership: "If not now, when?"^[11] (referring to the option of a referendum on the issue)

He joined the Panel of Chairs in 2010 and was co-chair of the Education Bill that went through committee in 2011. In May 2010, he was elected vice-chairman of the 1922 Committee and in the same year was elected to the Conservative Party Board.

House of Commons Procedure Committee: 2012–2019

In October 2012, Walker was elected as chair of the Procedure Committee, which decides on the process for election of a new Speaker of the House of Commons. In addition to his chairing duties, Walker is a member of the Speaker's Committee for the Independent Parliamentary Standards Authority (SCIPSA) and answers parliamentary questions on behalf of the committee.^[12]

In July 2013, Walker voted in favour of extending same-sex marriage to England and Wales.^[13]

In December 2013, Walker was the only MP to confirm he would accept an 11% pay increase.^[14] His championship of the pay rise and membership of the committee led to him being described by The Daily Telegraph as being in with an outside chance of becoming speaker when John Bercow stood down.^[12]

In the last parliamentary session before the 2015 general election, Walker explained what he knew about the Government decision to force a vote on changing the rules for electing a speaker for the next Parliament, in order to remove the then-Speaker John Bercow.

Walker said he had written a report on the subject "years ago" but although he had talked to William Hague and Michael Gove that week, neither had told him their objectives. He had only found out via the grapevine, and stated that he would rather be "an honourable fool" than part of a plot. The government lost the vote and Walker received a standing ovation from Labour MPs.^[15][16]

Following the 2015 general election, Walker was returned unopposed as chair of the Procedure Committee.^[17]

Walker was appointed an Officer of the Order of the British Empire (OBE) in the 2015 New Year Honours for political service,^[18][19] and was appointed a Knight Commander of the Order of the British Empire (KBE) in Theresa May's resignation honours on 10 September 2019, "for political and public service".^[20]

In May 2019, Walker and Cheryl Gillan became acting chairs of the 1922 Committee after Graham Brady resigned to consider standing in the leadership contest to succeed Theresa May as Conservative leader. They stood down when Brady returned to the role in September of that year.^[21]

Criticisms of COVID-19 lockdown restrictions: 2020–2021

In response to the Johnson government's attempt to control COVID-19 through a three tier system, Walker said in October 2020 that the government seemed to think it could "abolish death". He also accused the government's Scientific Advisory Group for Emergencies of choosing to "ramp up" the "fear factor" regarding the disease.^[22] Regarding the second tier regulations in November, Walker said "As we drift further into an authoritarian coercive state, the only legal mechanism left open to me is to vote against that legislation. The people of this country will never, ever forgive the political class for criminalising parents seeing children."^[23]

In November 2020, Walker called police officers a "disgrace" for enforcing government laws surrounding COVID-19 by arresting a 72-year-old woman who was "peacefully protesting" and who was charged under the Coronavirus Act.^[24] At the time, Walker called for the Constitution of the United Kingdom to be codified into a single written document (it is currently uncodified) to prevent further curbs on civil liberties.^[25]

On 25 March 2021, following a debate on the six-month extension of emergency powers during the COVID-19 lockdown, Walker made a widely reported speech in which he said:

For the next few days, I will walk around London with a pint of milk on my person because that pint will represent my protest. And there may be others who will choose too to walk around London with a pint of milk on their person as well and, perhaps, as we walk past each other in the street, our eyes might meet. We might even stop for a chat.

The speech was described as "surreal" by The Guardian,^[26] "bizarre" by The Independent,^[27] "astonishing" by Yahoo,^[28] and "odd" by indy100.^[29]

On 18 April 2021, Walker published an op-ed in The Daily Telegraph in which he stated his concern about the rumoured COVID vaccine passports, specifically by drawing parallels to other public health concerns not managed in the same way, such as obesity.^[30]

Retirement from the House of Commons: 2022–present

On 1 February 2022, Walker announced he would be standing down at the next general election, saying there had been "a lot of grief and pain" in the country which had meant politics had become a "pretty toxic environment".^[32]

Walker endorsed Penny Mordaunt during the July 2022 Conservative Party leadership election.^[33] He became the fifth Conservative MP to publicly call for the Prime Minister Liz Truss to resign.^[34] During the government crisis on 19 October 2022, Walker called the Truss ministry "a shambles and a disgrace... utterly appalling", commenting of its supporters that he had "had enough of talentless people" for whom "it’s in their own personal interest to achieve a ministerial position".^[35][36]