On 10 July 1989, Scottish striker and former Celtic star Mo Johnston signed for Rangers, igniting a firestorm of controversy across both sides of the Old Firm.
Johnston had been born and raised in Glasgow. In 1984, after beginning his professional career with Partick Thistle (1981-84) and then Watford (1983-84), he signed for Celtic, the team he had supported as a child. He was an immediate success for the Hoops, scoring 52 goals in 140 league appearances and helping them to the Scottish Cup trophy in 1985 and the league title in 1986. In 1987, he transferred to Nantes, where he played for two seasons.
In 1989, near the end of his second season with Nantes, Johnston announced his intention to return to Scotland and play again for Celtic. But just days after reaffirming his commitment to Celtic at a press conference at Celtic Park, he signed with their bitter rivals, Rangers. The move shocked and angered Celtic supporters, many of whom felt betrayed by a player whom they had previously supported and who had himself grown up supporting Celtic. He reportedly received several death threats.
Celtic supporters weren't the only ones upset, however. Many Rangers supporters were incensed that the club had signed a former Celtic player, due in no small part to the fact that he was a Roman Catholic. The Old Firm has traditionally broken down along religious and political lines, with Catholics and supporters of Scots-Irish independence mostly favoring Celtic, while Protestants and British Unionists generally side with Rangers. When Johnston signed for Rangers, he became the first Catholic to do so since the end of World War I (and had the highest profile of any previous Catholic signing). Thus, many Rangers fans reacted to the news of Johnston's signing by burning their scarves and season tickets in protest.
Johnston played only two seasons for Rangers, scoring 46 goals in 100 appearances and winning two league titles. He subsequently played for Everton (1991-93), Hearts (1993-94), Falkirk (1994-96), and the Kansas City Wizards (1996-2001), before retiring as a player and moving into management. He is currently the manager/director of football for Toronto FC.
Johnston's last-minute switch went unexplained for years until 2001, when his former agent Bill McMurdo revealed that the decision was neither his nor Johnston's, but was instead made by the company that owned Johnston's contract. According to McMurdo, that company simply sold him to the highest bidder, who happened to be Rangers.