Horne was previously part of a group of Fife youngsters who achieved a rare double, playing in the Bell Baxter High School team who won the Bell Lawrie Scottish Schools Cup and then in the Howe Of Fife squad who lifted the Scottish Youth League Cup. In season 2006–07, too, he was in the Bell Baxter team who won the Royal Navy schools sevens. He played for West of Scotlandin season 2008-09. He was drafted to Melrose in season 2009-10. He was drafted to Dundee HSFP the following season. He was drafted to Stirling County for 2011-12 and 2013-14 season. Drafted for the Hawks in 2014 and 2016, Horne was again been drafted to Glasgow Hawks in the Scottish Premiership for the 2017-18 season.
Professional career
Horne was a near-permanent fixture in the Glasgow Warriors squad that won the 2014–15 Pro12 title. He was named in the Pro12 Dream Team at the end of the 2014/15 season. He signed a new 3 year contract in 2017, taking him to the end of the 2019/20 season.
International career
Later in 2007, he played for Scotland in the Home Unions’ under-18 festival in Gloucestershire, and in 2008 he played international rugby at both under-19 and under-20 levels. He was in the Scotland team who beat Italy in the under-19 international in February at Parabagio, near Milan, and he then played for the national under-20 squad in all five matches in the IRB Junior World Championship in Wales in June, starting in three of the games. He moved from Howe of Fife to West of Scotland for season 2008–09 and signed up with Glasgow Warriors a year later. He scored all of Scotland’s points with six penalty goals in the 18–17 win against Wales in the 2009 Six Nations Under-20 Championship match at McDiarmid Park, Perth, in February. His tally was a Scottish record in the championship, and he added a penalty goal in each of the subsequent matches against France and Italy. However, that tally of 24 points was passed by Robbie McGowan later in the championship with 27. Peter took his under-20 year’s tally to 63 points when he scored 39 in starting in all five matches in the IRB Junior World Championship in Japan in June. Horne made his full international debut for Scotland on the 2013 summer tour to South Africa, during which he picked up a serious knee injury which kept him sidelined for almost a year. His first full home international came against Italy during the 2015 6 Nations.
Coaching career
Horne was a player-coach at Glasgow Hawks for 2017-18. He moved to an Assistant Coach role at Glasgow High Kelvinside for the 2018-19 season. On 21 June 2019 it was announced that he would be the Assistant Coach at Stirling County.
