Wallis was also a member of Team GB at the 2000 Summer Olympics in Sydney. Wallis, nicknamedWal, "Kipper" and/or Ratty, played club hockey for Teddington and Surbiton. He made his debut for England in 1995. He now works as a hockey coach and Physics teacher at Reed's School in Surrey.
He plays golf competitively, has played for the Surrey County Golf Union First Team and reached his lowest handicap in 2012 (plus 2). In 2014 he finished tied first at The Open Championship Regional Qualifying tournament at Hankley Common GC with a 3-under par score of 68.