Dave Reddin MBE has been made redundant from his post as Head of Fitness and Nutrition at the Rugby Football Union with immediate effect.
Reddin, 37, has spent eight years working with England teams and oversaw the conditioning and fitness regime of the side that won the Rugby World Cup in 2003.
His work with the senior England squad will be taken up by Calvin Morris, the RFU's National Fitness Coach.
RFU Elite Rugby Director Rob Andrew MBE today paid tribute to Reddin's contribution to England Rugby.
Andrew said: "Dave Reddin made a huge impact during his eight years with the RFU in developing a world class fitness programme to support the senior side.
"His work ensured that England arrived at the 2003 Rugby World Cup in peak condition and he was a major reason behind the team's success at that tournament.
"Dave goes with our thanks and best wishes for the future and I'm sure that he will continue to make a major contribution to elite sport in this country."
Dave Reddin said: "It has been a great privilege to have been involved with England over the past eight years and almost 100 test matches. I have worked with some absolutely incredible players and two outstanding coaches in Clive Woodward and Andy Robinson.
"Although the RFU have explained the rationale for their decision to make my role redundant I am disappointed to be leaving.
"I do feel proud to have been associated with the most successful period in English rugby history and my hope in leaving is that positive changes are made to recreate that."