From 2000 to 2001, Millar was mayor of the township of Towyn and Kinmel Bay.[3] He was also a member of Conwy County Borough Council, the North Wales Police Authority and the North Wales Fire and Rescue Service.[3] In 2006, while a member of Conwy Council, Millar was referred to the standards watchdog, after complaints from the Unite, Unison and GMB trade unions about comments he made alleging that staff were abusing or misusing the sick pay system.[4]
In the 2007 election, Millar was elected to the Clwyd West seat, unseating the incumbent Labour MS, Alun Pugh. Pugh was the only Cabinet Minister to be defeated in the election.[6]
After his election in 2007, Millar was appointed Shadow Minister for Environment and Planning by Nick Bourne.[9] He served in this role until February 2009, when he was moved to be Shadow Minister for Communities and Local Government.[10] In November 2010, he was appointed Shadow Minister for Economy and Transport.[11][12]
After his re-election in 2011, he was appointed Shadow Minister for Health by interim leader Paul Davies.[13][14] He retained this role after Andrew RT Davies was elected leader and formalised the interim Shadow Cabinet, and throughout the remainder of the term.[15] After the 2016 Senedd elections, Millar was appointed Welsh Conservative education spokesperson, as Plaid Cymru became the Official Opposition.[16] In April 2017, he became Shadow Minister for Education, as the Welsh Conservatives returned to opposition.[17]
Millar was discussed as a candidate to replace Andrew RT Davies at the 2018 Welsh Conservatives leadership election, but he did not contest the election.[18] After Paul Davies was elected as leader of the Welsh Conservatives, Millar was appointed as Welsh Conservative Chief Whip, Welsh Conservative Policy Director, and Shadow Cabinet Secretary for External Affairs and International Relations.[19]
In January 2021 the Senedd Commission investigated Millar for an alleged breach of COVID-19 regulations.[20] He resigned from his frontbench roles on 23 January 2021 after the leader Paul Davies resigned on the same day.[21] Both Millar and Davies were later cleared of any wrongdoing by South Wales Police, Cardiff City Council, the Senedd Commission and the Senedd Standards of Conduct Committee. In April 2022 a report published by the Senedd Standards Committee found that no laws or standards of conduct had been breached.[22]
He returned to the role of Chief Whip in May 2021, after the 2021 Senedd election, alongside a role as Shadow Minister for the Constitution and North Wales.[23]
He is a former member of the Senedd's Sustainability Committee, and a former Chair of the Senedd's Health, Well-being and Local Government Committee.[citation needed] In November 2010 Millar was elected as Chair of the Senedd's Public Accounts Committee. Millar also Chairs the Cross Party Group on Faith, and the Cross Party Group on the Armed Forces and Cadets, both of which he is a founder member.[citation needed]
