Britain has failed to use the Olympics to create a "transformational change" in society, the woman credited with masterminding Team GB's record medal haul has told The Independent on Sunday.

Baroness Sue Campbell, the former PE teacher who provided the strategy behind British athletes' spectacular performance at the Games, said that it is not too late to create a genuine Olympics legacy – but many opportunities have already been missed.

Baroness Campbell, who as chairman of UK Sport has been a fiery presence for the past decade, said that while elite athletes now have "a high performance system that is amongst the best in the world," in other areas – such as grassroots sport, volunteering and women's participation in exercise – Britain has not secured the legacy it could.

"If I'm really honest, I think there's a lot of investment in sport and there's a lot of activity going on," she said, "but in a generation's time will we look back and think 'that was the moment'?

"I don't think we've grabbed [these issues] in the way we could have done. I think we can still do it, but it's about getting real focus on some of these big transformational issues."

Baroness Campbell said that weak strategy for school PE lessons and the lack of investment in coaching were also stopping greater participation in sport.

Her comments come ahead of a major report into the social impact of the Games, which will be published this Wednesday by the Legacy Trust, the charity set up in 2007 to ensure post-Olympic change.

They also come ahead of expected excitement this summer at the so-called "Anniversary Games", where British track medallists such as Mo Farah and Jessica Ennis will join Usain Bolt at the Olympic Stadium for two days of elite athletics.

Commenting on why she singles out volunteering, grassroots sport and women's participation, she said: "I'd pick those because they were the things which captured people's imagination in London...and those are the big visions that if caught and really driven, could have a big impact not just on sport but on society – which quite frankly is what we should all be worrying about."

In what will be interpreted by many as an attack on Sport England, the body responsible for sport's grassroots, Baroness Campbell said: "We need some consistency on sports policy. I think it takes a long time for good policy to really get through the system on to the ground and if, no sooner than you get it on the ground it goes again, then it's no good."

Public servants have failed to stand up to politicians, she said. In her ongoing role as chairman of the Youth Sport Trust, a charity which works to improve children's sport, she is understood to have clashed frequently with Sport England for their failure to hold the line against political fashions.

Speaking about standing up to ministers' fads, she said: "Occasionally, you have to say 'no'... If you don't do that then you are subject to this constant change. Either you have to trust that there are people out there with expertise who can advise, or you have to say you're going to change policy every few years and see if anything sticks."

Baroness Campbell said that not enough thought was being put into getting women more active. "What we can't do is work under the assumption that they'll participate because we tell them that sport's good for you.

"You've got to get into their minds which is, 'I want to look good, I want to do better at work, I want to be attractive to the opposite sex.' You've got to get into people's minds and think, how do we present activity as a way of helping you do that, not 'Sport's good for you, come and have a dose of it' like a medicine. No. Not going to do it."

The spirit of the Olympic volunteers in their purple uniforms provided one of the lasting memories of London 2012. Campbell said she was "not sure" that the goodwill of the Games Makers had been "capitalised on enough" to create something bigger for British society. "We could have lifted it to make volunteering, instead of just an old-fashioned thing that old people do, something much more modern."

Completing a list of Britain's legacy failings, she said school PE lessons need to be looked at. Ring-fenced funding for school sport was abandoned in 2010 and instead two years of £150 million funding for PE was announced last month. "If you leave this to 18,000 head teachers to decide how to spend this money I think some will make great choices and I think many might not," she said.

A lack of investment in coaching was, she said, another reason for the country's failure to better capitalise on the Games for everyday people. "If you want to create transformational change at a whole range of levels in sport you would invest major money in coaching. Because for most people, the thing that keeps them in sport are coaches and right now we still have a coaching workforce that is very transient and made up of volunteers."

After 10 years at the helm, Baroness Campbell is stepping down as chairman of UK Sport, which distributes government and Lottery money to elite athletes. Last week it was announced that the new chair will be Rod Carr, former chief executive of the Royal Yachting Association.

Some in Westminster are pleased to see her go, Campbell says. "I haven't always been easy to work with. I'm pretty determined and I've felt a very strong allegiance to do what's right for sport and that hasn't always necessarily been compatible with where different secretaries of state or ministers thought I should be going.

"It's been a colourful journey and so maybe they're quite relieved to see the back of me."