[4] His mother, Jill Tambaros (née Golding),[5] is a supply teacher, and his father, Mick Mather, is a support worker.

[14] Intent on becoming an MP,[6] Mather studied for the MPP at Oxford's Blavatnik School of Government as a Political Leadership Scholar in a scheme that was "open to applicants from the UK and Republic of Ireland who intend to run for public office".

[17] Whilst at Oxford University, Mather worked as a researcher for The Times journalist and former Conservative MP Matthew Parris.

[18] Mather then worked as a public affairs adviser for the Confederation of British Industry for 18 months before entering Parliament and was a parliamentary researcher for Labour MP Wes Streeting from 2019 to 2020.

[20][21] The previous Conservative majority of 20,137 votes, secured the resigning MP Nigel Adams in the 2019 general election, was the largest ever overturned by Labour in a by-election.

[14][25] Multiple Labour politicians, including party leader Sir Keir Starmer, criticised Mercer's comment.

[26] The Guardian noted that former UK Prime Ministers William Ewart Gladstone and Winston Churchill first became MPs at the ages of 22 and 25 respectively.

In interviews with BBC News and The Press from the same month, Mather said his main priority as an MP was to support people affected by the cost of living crisis.

[29] In 2023, Mather said he supported Labour leader Keir Starmer's policy of maintaining the two-child benefit cap, adding: "I think we're going to inherit an absolute economic mess from the Conservatives when we take power and we're going to have to make extremely difficult decisions once we do, and I support the Labour government in doing so.