Martin Johnson has accepted responsibility for England's World Cup failure on and off the field and resigned as team manager six weeks before the end of his contract and eight months after a first Six Nations title in eight years.

The Rugby Football Union announced the decision on Wednesday morning and Johnson later confirmed his departure at a Twickenham media conference, the day before the Professional Game Board was due to review his position and that of his management team.

Johnson said his decision was the right one for the team. "I've given this a huge amount of thought since we returned from the World Cup and didn't come to this decision lightly," he said. "I think it's in the best interests of myself and the England team that I don't continue on into next year.

"It's been a fantastic three and a half years. I've worked with some fantastic players and a great coach and management group. Whilst we've had our most successful season with 10 wins from 13 we are disappointed with how we ended it with the World Cup. I think it's the right decision at this time."

While there was support on the board for Johnson remaining in the position he assumed in the summer of 2008, there was a strong feeling that his team of coaches, including Brian Smith and John Wells, needed shaking up. Johnson's belief has always been that the man in charge should have the power to appoint his own team and that any failure is collective rather than individual.

It was his stance in 2006 when the RFU sacked the then head coach Andy Robinson's back-up team but kept him in place. Johnson asked the question in a television interview later that year whether Robinson should also have gone, correctly predicting he would not last long in the job, and whatever his faults as team manager, hypocrisy is not one of them.

Johnson feels let down more by his players than his coaches, even if England did not get it right tactically during the World Cup. Last week's decision by the RFU, after a disciplinary process, to fine Mike Tindall £25,000 and throw him out of the elite squad showed how the manager's faith in his charges had been misplaced.

Johnson vigorously defended Tindall, a fellow 2003 World Cup winner in Sydney, after details emerged of a riotous night out in Queenstown enjoyed by some of the players following the opening group game against Argentina. "Rugby player drinks a few beers shocker," was Johnson's dismissal of what he felt had been a strong overreaction based on what he had been told.

It emerged, much to Johnson's anger, that it had been more a case of a few beers too many and it was the start of a rash of incidents off the field that dogged the campaign. The media were blamed, but they were only firing a gun that had been loaded for them.

After one media conference that had dealt exclusively with what England players had been getting up to rather than rugby, Johnson walked out of the room muttering an expletive. It was aimed at the reporters he had just left, but could also have been applied to his players.

One of the reasons for Johnson's appointment, some six months after England had reached the 2007 World Cup final, was that the RFU felt he would bring a clarity to selection and inject discipline into the squad. He succeeded in neither and his lack of experience in management or coaching, which were felt by the union to be inconsequential, told.

Johnson's record was 21 victories in 38 Tests, which compared favourably with England's record between 2004 and his appointment, and there was an argument that, having gained the experience he lacked when he was appointed, he should have been charged with taking the team to the 2015 World Cup.

A problem was the muddled thinking that has beset the RFU for too long, something Johnson identified in 2006 when he said: "When Clive [Woodward] went [as team manager in 2004] I'm not saying appointing Andy [Robinson] was wrong but who made that decision? Was it guys who really knew what decision they were making? The recent appointment of Rob Andrew [as elite rugby director] should have been made at least two years ago, so they had a guy with current rugby knowledge planning the succession of coaches and players."

Andrew is still in place, although his position will be the subject of a wide-ranging review which is due to start next year, after a chief executive is appointed. The England team came to reflect the RFU at the top, heading in an uncertain direction.

Perhaps now the RFU will stop looking to 2003. Woodward was succeeded by his forwards coach then, Andy Robinson, who in turn was replaced by Brian Ashton, the men in white's attack coach for part of the Woodward era, who in turn was dumped for the World Cup winning captain, Johnson.

The manoeuvring will now start to find Johnson's successor. Nick Mallett, the former South Africa and Italy coach, who was born in England, has already expressed his interest, although he has said he would want the job on his own terms: no reporting to a performance director and the freedom to appoint his own management team.

The RFU has little time to act with the start of the Six Nations less than three months away. It should go through a process of job advertisement and interviews, but it needs to make a quick decision. Having criticised England coaches and managers for so long for getting selection wrong, it is the selection of the governing body itself which has been just as random. There is little evidence it will get it right this time.

Johnson added at Twickenham: "It's been a fantastic three and a half years. I've worked with some fantastic players and a great coach and management group. Whilst we've had our most successful season with 10 wins from 13 we are disappointed with how we ended it with the World Cup."

Andrew paid tribute to Johnson's work and said: "When you work with someone you realise the effort they put in and he's worked tirelessly to move the team forward.

"We always said right the way through the process that Martin would take the team to the 2011 World Cup and then we could look if Martin wanted to continue in that role. It's important at this point in time that we respect Martin's decision. He's decided it's time to move on."

Andrew said he would not be following Johnson by quitting his post, adding: "No I'm absolutely not considering resigning. In terms of the department and the structure of the professional game – that's my role in this. My job is to run the department, not just the playing side of things."

Johnson refused to blame the off-field incidents that marred England's World Cup campaign for his departure, even though he admitted some frustration at what went on away from match-day in New Zealand.

"The off-field stuff didn't help," he said. "It portrays the team in a bad light and not in an accurate light. But we gave people the opportunity to report things as they did.

"I don't know about being let down. Of course it didn't help, we didn't want that reputation. I warned the players if they open door slightly it will get fully opened. They did that. How that affected performances on field no one can answer."

Johnson said he would leave without any regrets, adding he had carefully considered his decision to quit. "Before you go to a World Cup you think what you want to do post World Cup – it's not a knee-jerk reaction," he said. "It's a thoughtful and considered opinion. On field I think we made huge strides. The players we brought in over the past 12-18 months have become first-choice established.

"They have been to a World Cup and won a Six Nations. Part of me regrets leaving the job in these circumstances. There is unfinished business and a feeling to put things right. But I won't leave with any regrets."