In a resignation letter seen by The Yorkshire Post, Mr McMillan, a former senior partner at PriceWaterhouseCoopers, said he felt it was a “logical time” to go after two investigations into expense spending and management culture were confirmed following the controversial departure of ex-chief executive Sir Gary Verity last month.
Mr McMillan, who had been in the post at WTY since 2015 after previously running PwC’s Leeds office, had come under increasing pressure for his handling of the circumstances of Sir Gary’s departure and delays in setting up the inquiries which have been established.
Last week, a group of council leaders who had given millions to WTY through the Leeds City Region business rates pool wrote him an open letter demanding “rapid changes in governance” if they were to continue their long-term funding of the tourism agency.
WTY is a private company but receives around half its £4m annual income from the public purse, largely from local councils.
Wakefield Council leader Peter Box told The Yorkshire Post on Wednesday that his authority would not continue to support WTY until Mr McMillan departed but it is understood his decision to resign had already been taken by that point.
Mr McMillan’s resignation letter said: “The investigations we have put in place have now commenced and having overseen that process, I have decided that now is the logical time for me to step down from the board.
“It is clear that our local authority major sponsors are looking for a significantly revamped board to take the business forward.”
His letter added that he was proud of WTY’s achievements in recent years in helping to grow the value of tourism to the region’s economy from less than £6bn in 2011 to £9bn by 2017.
He said that WTY’s work to secure the opening stage of the Tour de France in 2014 and subsequently establish the Tour de Yorkshire had put the region “on the map as a tourist destination”.
“Local authorities have, in particular, benefited by the success of the Grand Depart of the Tour de France and from the now well-established Tour de Yorkshire,” he said.
“Our members understand the value they receive from Welcome to Yorkshire and have been extremely supportive through what has been a difficult period. I am grateful to all of them and thank them for their continued support.
“Looking ahead, I hope Welcome to Yorkshire will continue to make an outstanding contribution to Yorkshire’s economic growth.”
He also thanked the board and paid tribute to the WTY workforce in his farewell letter to colleagues.
“More important than all the above is for Welcome to Yorkshire to look after its very talented and extremely loyal employees.
“The contribution each of them makes to the business, including during what has been a difficult period for us all, as always, goes above and beyond the call of duty.
“My thanks goes to every one of them for their continued support of an organisation I know they all feel proud to be part of. I shall miss them all.”