 He was the youngest ever Roses Match debutant, that year, when he played for Yorkshire against Lancashire at the age of 17.Thornicroft appeared in only one first-class match during the following season, although he played in five Youth One Day Internationals and three Youth Tests during the calendar year of 2003, both during an English tour of Australia, before coming back home and playing two Youth Tests against South Africa.Thornicroft spent 2004 and 2005 playing little first-class cricket, although he continued in a consistent vein of form when sent out on loan to Essex's Second XI.