His time as chairman of Plymouth Argyle resulted in the club entering administration with debts of over £17 million and accusations of financial mismanagement.

[1] Born in Brentford, he was the eldest son of a carpenter, Roy Thomas Gardner, and his wife Iris Joan (née Paine) and was brought up in Middlesex and Surrey in humble surroundings.

Gardner joined British Gas in November 1994 as executive director, finance and was involved in splitting the company into two parts.

[8] In 2014, he joined the board of William Hill as senior independent non-executive director, serving as a member of the Audit and Risk, Remuneration, Nomination and Corporate Responsibility Committees.

[9] In 2015, Gardner became chairman of Serco, the British outsourcing company which operates public and private transport and traffic control, aviation, military weapons, detention centres, prisons and schools.

[11] He was a director at Willis Towers Watson until January 2016 and is currently a Senior Adviser to Credit Suisse, providing counsel to clients in a variety of sectors including energy, utilities, industrials and leisure and services.

[21] He was appointed as non-executive chairman of Manchester United plc in November 2001, taking over from Sir Roland Smith on 31 March 2002.

[3][21] In April 2005, he and the Manchester United board issued a statement recommending against the proposed buyout by Malcolm Glazer and his family, saying the "proposed capital structure […] still contains more leverage [debt] than the board would consider prudent"; however, they were forced to issue a contrary statement a month later, once the Glazers had acquired enough shares to constitute a majority stake in the club.

[22] Gardner resigned as chairman in June 2005, shortly after the Glazer takeover, as did his fellow non-executive directors Jim O'Neill and Ian Mutch.

He stated that it was the consortium's ambition to see Argyle promoted to the English Premier League within five years and focused on the club's bid to host the World Cup finals in 2018.

[26][27] In March 2010, the club announced that Home Park was to be transferred to the holding company owned by Gardner, Todd and Yasuaki Kagami.