Unlike many other cross-code converts of the period, Tait had the benefit of growing up in Cumbria, where his father, Alan Senior, was playing for Workington Town. However, Tait played Union first and made his Test début for Scotland in the inaugural 1987 World Cup held in New Zealand where, he came on after seven minutes as a replacement in a 20–20 draw with France in Christchurch.
With the advent of Rugby Union turning profession Tait along with many other converts switched codes back to union in 1996 signing for the Newcastle Falcons with whom he won the Premiership in 1998, making 19 appearances that season. At first he was ignored by the Scotland selectors but eventually made his return for Scotland after a nine-year absence in 1997 and went on to represent the British & Irish Lions in South Africa also in the summer of that year. Surprising many Tait was selected to start the first two Tests on the wing, even though his favoured and more recognised position was at centre. This was due to coach Ian McGeechan believing that Tait would add extra defensive capabilities to the backline over the other wingers, in what would be a tight test series. He famously scored a try in the first match as the Lions won 25–16 in Cape Town. He also played in the second match which saw the Lions clinch the series after a dramatic 18–15 victory in Durban. Injured before the 3rd Test he did not play as the Lions lost the last match 35–16. For Scotland Tait developed a devastating partnership with John Leslie. Many saw their pairing as instrumental in Scotland's good performances of the time and allowing stand-off Gregor Townsend to exploit gaps in the opposition defence. This was no more apparent that in the 1999 Five Nations Championship where Townsend would become the fifth and last player in history to score a try against each of the other countries in the five nations tournament. The championship culminated in Scotland narrowly finished ahead of England on points difference thanks to Wales' last minute victory over England at Wembley. Tait scored two tries in Scotland's last match of the tournament as they put in an historic performance to beat France 36–22. Later that year he represented Scotland for the last time at the 1999 World Cup finishing with a defeat by the All Blacks. He scored a try against South Africa in the pool stages at Murrayfield in a 46–29 reverse to the holders. In 2000 Tait retired from professional rugby finishing his last game playing for his last club Edinburgh Reivers. In all Tait played 27 times, scoring 17 tries, for Scotland, this is an exceptional record especially when considering that the bulk of these games were played after his return from League at the age of 32. Partly because of this it is why Tait is still regarded in high esteem by Scotland supporters to this day.
Coaching
Following his retirement from playing he then moved into coaching, initially working with Scotland as a defence coach. Although he was dismissed from the post by Matt Williams he was later restored to that role by Williams successor Frank Hadden. In 2004 he joined the Borders as a defensive coach. Tait then moved back to the Falcons as an assistant before assuming the top job at the Premiership club as part of a restructuring process in the wake of Steve Bates' departure from the post of director of rugby in 2009. He held the position of Head Coach of Newcastle from 2009 to 2012 until club owner, Semore Kurdi announced Tait was 'taking a break from rugby' following a series of poor results.
