Marshall received his elementary education while attending Gunnedah South Public School before completing his secondary studies at Farrer Memorial Agricultural High School where he earned the higher school certificate. In his final year he was voted by his peers as the "person most likely to be Australian Prime Minister", which is a prediction he is also said to have made as a youth, to fellow students on the school bus.
Political career
Elected to Gunnedah Shire Council in 2004, aged 19, Marshall became deputy mayor and then mayor of Gunnedah, an office his father once held, after the 2008 local government elections. During his time as Mayor, Marshall served as president of the Country Mayors' Association and Senior Vice-President of the Shires Association of NSW. Marshall moved to Armidale in 2012, resigning from the Council, and commenced studying commerce at the University of New England, prior to his endorsement as a candidate for the March 2013 by-election held after sitting independent member Richard Torbay was forced out of politics amid allegations of corruption. Marshall would claim victory on election night having receiving over 60% of the vote, subsequently being declared the winner with a margin of more than 30%. This was not considered an upset; in 2011, the Nationals would have won it with a majority of 26.1 percent in a "traditional" matchup with Country Labor. Marshall won a full term almost as easily in 2015, boosting his majority to 27.1 percent, the third-safest in the state. He was reelected in 2019, and now sits on a majority of 32.8 percent, the safest in the state. During his preselection bid ahead of the Northern Tablelands by-election in 2013, it was revealed that Marshall once held concurrent membership with both the Nationals and Labor from 2001 to 2003, while also being employed on the staff of independent Member for Tamworth, Peter Draper. Country Labor organiser Courtney Roche said Marshall would have been deemed to be a card carrying member of the party until 2004, after which his membership expired. On 27 June 2014, Marshall was stopped for a random breath test while driving and returned a blood alcohol reading of 0.112. On 15 July he pleaded guilty to and was convicted for mid range drink driving. Marshall's counsel argued in mitigation that he was suffering from a head cold which may have impaired his awareness of his level of intoxication. He was disqualified from driving for nine months and fined $2,000. It was subsequently revealed that Marshall had incurred 17 speeding offences since 2002, and that his licence had been suspended on three separate occasions between 2003 and 2011. He was able to avoid a fourth suspension in May 2014 by entering into a good-behaviour bond. Having served on several standing, select and statutory Parliamentary Committees, as well as in the position of Temporary Speaker, Marshall was appointed to the position of Parliamentary Secretary for Northern New South Wales and Renewable Energy on 25 August 2016. Following the resignation of Mike Baird as Premier, Gladys Berejiklian was elected as Liberal leader and sworn in as Premier. The first Berejiklian ministry was subsequently formed with Marshall sworn in as the Minister for Tourism and Major Events, and Assistant Minister for Skills with effect from 30 January 2017. Following the 2019 state election Marshall was appointed as the Minister for Agriculture and Western New South Wales in the second Berejiklian ministry with effect from 2 April 2019.
