[9] Grant led the criminal investigation into Catholic priest Father Vincent Ryan and has said "there is nothing I would not do in order to protect the children of NSW" from sexual abuse.

[6] In 2020, Grant featured in the ABC documentary series Revelation, where he told Sarah Ferguson how he investigated and charged Vincent Ryan on allegations of child sexual abuse.

[5][16][17] On 15 October 2014, Andrew Stoner stood down as Nationals leader and Deputy Premier, citing family reasons.

On 16 October Grant was elected party leader and the following day he was sworn in as Deputy Premier of New South Wales, assuming the majority of Stoner's former ministerial responsibilities.

[6][18] Following a period of leadership speculation which came to a head on 12 November 2016 after the Nationals' poor performance at the Orange state by-election, on 14 November, Grant, facing a leadership spill, announced his resignation as Nationals leader and Deputy Premier, effective the following day.

On 21 March 2017, ABC News reported with a headline Mr Grant NSW Police Minister fined for using phone in car, says he didn't know it was illegal.

The NSW Water Minister Kevin Anderson announced that he would be working with the Murray–Darling Basin Authority to address Grant's comments, stating "I look forward to continuing to work with the Murray Darling Basin Authority to establish the most effective short and long-term solutions that will balance the needs of the environment, community and farmers while improving drought security".