Marchant won caps for Great Britain while at Castleford in 1986 against France, and Australia. In 1986 Marchant played a handful of games for Brisbane Rugby League club, Wynnum Manly Seagulls, who won the premiership that year. Marchant won caps for Yorkshire while at Castleford; he played left-, i.e. number 4, and scored 1-try in the 26-14 victory over Lancashire at Leeds' stadium on 17 September 1986, played right-, i.e. number 3. and scored 1-try, in the 16-10 victory over Lancashire at Wigan's stadium on 16 September1987, played right-, and scored 1-try in the 28-4 victory over Papua New Guinea at Leeds' stadium on 27 October 1987, and left-, and scored 1-try in the 24-14 victory over Lancashire at Leeds' stadium on 21 September1988. Tony Marchant played right-, i.e. number 3, and scored the first try in Castleford’s 15-14 victory over Hull Kingston Rovers in the 1986 Challenge Cup Final during the 1985–86 season at Wembley Stadium, London on Saturday 3 May 1986. Tony Marchant played right-, i.e. number 3, in Castleford's 2-13 defeat by Hull F.C. in the 1983Yorkshire County Cup Final during the 1983–84 season at Elland Road, Leeds on Saturday 15 October 1983, played right-, and scored 2-tries in the 18-22 defeat by Hull Kingston Rovers in the 1985 Yorkshire County Cup Final during the 1985–86 season at Elland Road, Leeds on Sunday 27 October 1985, played right- in the 31-24 victory over Hull F.C. in the 1986 Yorkshire County Cup Final during the 1986–87 season at Headingley Rugby Stadium, Leeds on Saturday 11 October 1986, played right- in the 12-12 draw with Bradford Northern in the 1987 Yorkshire County Cup Final during the 1987–88 season at HeadingleyRugby Stadium, Leeds on Saturday 17 October 1987, played right- in the 2-11 defeat by Bradford Northern in the 1987 Yorkshire County Cup Final replay during the 1987–88 season at Elland Road, Leeds on Saturday 31 October 1987, and played right- in the 12-33 defeat by Leeds in the 1988 Yorkshire County Cup Final during the 1988–89 season at Elland Road, Leeds on Sunday 16 October 1988. Tony Marchant played, i.e. number 5, in Bradford Northern's 2-12 defeat by Warrington in the 1990–91 Regal Trophy Final during the 1990–91 season at Headingley Rugby Stadium, Leeds on Saturday 12 January 1991, and played, i.e. number 2, in the 15-8 defeat by Wigan in the 1992–93 Regal Trophy Final during the 1992–93 season at Elland Road, Leeds on Saturday 23 January 1993. Tony Marchant played right-, i.e. number 3, in Castleford's 10-18 defeat by Hull Kingston Rovers in the 1983–84 Rugby League Premiership Final during the 1983–84 season at Headingley Rugby Stadium, Leeds on Saturday 12 May 1984, in front of a crowd of 12,515, and played left-, i.e. number 4, and scored a try in Bradford Northern's 6-28 defeat by Widnes in the 1989–90 Rugby League Premiership Final during the 1989–90 season at Old Trafford, Manchester on Sunday 13 May 1990, in front of a crowd of 40,796.