Kay joined Leicester Tigers from Waterloo in 1999 and first played during the World Cup, with Tigers' normal Second rowsMartin Johnson and Fritz van Heerden away with England and respectively. With the help of Johnson and van Heerden, he developed his game, becoming a highly rated middle line-out jumper, like van Heerden. He was a member of Tigers' Heineken Cup winning sides in 2001 and 2002 as his international career blossomed. Having made his England A début against France A in Blagnac in 2000 Kay led England A to a 23–22 win over France A at Redruth in April 2001, and was called up for England's successful tour of North America and Japan that summer. He made his England début against Canada on 2 June 2001 displacing Danny Grewcock from the England side. After another outstanding season he was named as the Tigers Members' Player of the Year 2001/2, and was a nominee for the Zurich Premiership Player of the Year. He was in the starting line-up for all the Six Nations games in 2002, and scored a try against Ireland. After touring with England to Argentinain the summer of 2002, where he scored his second try, Kay went on to compete in both the Autumn internationals and the Six Nations, before touring to New Zealand and Australia in June 2003. Kay confirmed his status as a core part of the England squad in the World Cup when he played every minute of every England game except the game against Uruguay. His line-out skills came to the fore here, particularly during the games against South Africa, when Kay learned to count to ten in Afrikaans to crack the Springboks' line-out codes. During the final against Australia, Kay famously knocked-on in a try-scoring position when a try would have almost certainly meant an England win. England won regardless, partly as a result of Tigers' teammate Lewis Moody winning a line-out Kay himself had called. Sir Clive Woodward selected him for the 2005 British and Irish Lions tour to New Zealand. Kay came off the bench against Argentina in an official Test prior to the tour. Kay started in the first Test of the series. He was the only player to play every minute of England's 2007 Rugby World Cup campaign culminating in their narrow loss in the Final. He was one of only four players to have started both the 2003 and 2007 RWC Finals, the other three being Jonny Wilkinson, Jason Robinson and Phil Vickery. Kay helped Leicester win the Premiership in 2007, starting the final as they defeated Gloucester. Kay was a used replacement in every game of the 2008 Six Nations. He started both the 2008–09 Heineken Cup final and the Guinness Premiership win the same season. The Tigers won back-to-back Premiership titles the following season, in the 2009–10 Guinness Premiership, by beating Saracens 33–27 at Twickenham, though Kay did not feature in that game. He decided to retire at the end of the 2009–10 season after 11 years with Leicester Tigers. He has since worked as a commentator for ESPN and BT Sport.
Personal life
Kay is a supporter of Liverpool FC. In 2002 Kay married long-time girlfriend Virginia, a physiotherapist, and they have two children. His longtime Leicester Tigers and England teammate Martin Johnson was an usher at his wedding. Kay paid his respects to his former sports teacher at Merchant Taylors, Ian 'Robbo' Robinson, who died in a white water rafting incident whilst on a rugby tour with the school.