After leavingMount Florida School aged 18, Harkness joined his local side Queen's Park in 1925 and stayed there for three seasons. In line with their Corinthianideals, he played as an amateur during his spell at Hampden. Despite playing against professional and semi-professional sides, the Spiders managed to maintain a respectable position in Division One and Harkness was soon regarded as a key component in the side. In May 1928 aged 20, Heart of Midlothian lured Harkness into the professional ranks, making him their highest paid player in the process. Hearts were frequent top five finishers and the increased profile this afforded Harkness allowed him to become a regular international player. The Maroons of this era were a talented yet inconsistent side however, and during his 9 seasons in Gorgie, Harkness failed to win any major honours. A prime example of Hearts' unpredictability was season 1932–33, when both reigning champions Motherwell and eventual champions Rangers were defeated, yet dropped points to lesser sides ensured they only achieved a third-place finish. Harkness won the admiration of Celtic fans in an incident involving CelticforwardJimmy McGrory. In a match between Hearts and Celtic, McGrory made a dive in an attempt to score with a header. However, Harkness realised McGrory was going to collide against the goalpost, and as such pushed the Celtic player away round the post to protect him from serious injury. The Celtic fans shouted for a penalty and booed the Hearts goalkeeper for the remainder of the game. McGrory, however, highlighted his gratitude for Harkness' action and the following season in a game between the two clubs, the Celtic fans gave Harkness a prolonged ovation as he took up his position in goal. Willie Waugh displaced Harkness as Hearts' regular goalkeeper in 1936–37. After spending the remainder of the season as a reserve, Harkness decided to retire, at the comparatively young age of 29, to pursue a career in sports journalism. He wrote for the Sunday Post throughout the 1950s and was awarded an MBE in 1971.
International career
In total, Harkness played for Scotland on 12 occasions between 1927, when he made his debut in a 2–0 victory over Ireland at Windsor Park, and 1933. Scotland won eight and lost four of these matches, with Harkness twice recording a clean sheet. In 1928, Harkness was selected for the annual Scotland-England match in the Home Championship, a game which was to become part of Scottish football folklore. An unfancied side, in which the entire forward line measured 5' 7" or less, recorded a resounding 5–1 triumph and earned the moniker "the Wembley Wizards".
