Delon began playing rugby at the age of eight for Richmond RFC before moving to France, where he played for Racing Rugby Club de Nice and represented France at U16 level.

On his return to England, he joined the London Irish Academy in 2002, where his speed, skill and courage soon became apparent. He went on to play for England U19s and England U21s before being named in the England Sevens squad for the 2004-5 season, the same year in which he was named London Irish Young Player of the Season.

His progress through the ranks at London Irish has coincided with the team's rise to prominence in the English game, while his versatility and eye for the line has seen him establish himself as a cornerstone of one on the most feared backlines in European rugby.

His prolific try scoring ability, which has seen him cross the whitewash 50 times in 158 appearances, soon got him noticed by the international selectors and he was called up to the 2006 England Saxons squad for the Churchill Cup.

The step up to the senior side was only a matter of time and after being fast-tracked into the Senior Elite Player Squad in November, Armitage became the emerging talent of the 2008/09 season.

He won his first cap against the Pacific Islanders, a performance which was described by England Team Manager Martin Johnson as one of the best debuts he had ever seen, earning him the Man of the Match award.

He continued that form throughout the international season, featuring in all of England's RBS 6 Nations matches and earning a nomination for the Player of the Tournament award.

On the club front, Armitage's performances helped the Exiles to the 2009 Premiership final, gaining the club's Player of the Season award in the process. The 2009/10 season looked to have started with great promise for Armitage as he scored the opening try in Irish's 40-10 defeat of Gloucester during the first home match of the season at Madejski, but a shoulder injury sustained later in the match saw him ruled out of action for the next three months.

After falling down the international pecking order, Armitage's international fortunes were revived when he came off the bench in June 2010 to help England beat Australia on their home turf for only the third time in their history. His performances on the tour were duly rewarded with a place in the England EPS Elite squad for the2010/11 season.