Britain's much-trumpeted Olympic legacy, which promised to "inspire a generation", looks set to fail just 54 days before the world's biggest sporting event opens in the capital. Participation in most major sports is plummeting, a litany of cuts has left a slew of half-finished projects and almost half of all young people believe they do not get enough opportunity to play sport in school, The Independent on Sunday can reveal.

Sebastian Coe said he wanted to "change the face of British sport" when he brought the Olympics to British soil, and there were promises that the Games would make the country more active. Yet senior figures in British sport warned last night that hopes of an Olympic legacy had been "dismantled" by cuts.

Among schemes that have closed or had their funding slashed since London won the Games bid are school sports, the budget for which has been cut from £162m to just £35m, resulting in thousands of sports coaches and co-ordinators being sacked; free swimming for under-16s and over-65s; County Sport Partnerships, which lost £3m; and Cycling England, which was funding 18 towns to improve cycle routes when it was shut.

Baroness Campbell, chair of both UK Sport and the Youth Sport Trust, said budget cuts forced schools to lay off the people who could boost interest among children. "Facilities are great, but in the end it's people that get you active", she said. "We had 3,400 school sports co-ordinators and when the money went they went. We've created some infrastructure with the School Games, but we've lost that human energy that was making stuff happen."

She warned that while the legacy of bringing on more elite athletes has been a success, the chance of capitalising on the Games for ordinary people risked being squandered. "The reason we've been able to build a high-performance legacy is that we've had the same policy for the last 10 years and we've worked at it," she said. "One of the problems for the participation legacy is it changes frequently so it's hard to make a lasting impact."

Programmes that promote healthy activity were also cut. Grants for 1,300 proposed playgrounds were scrapped, while Walking for Health had its government funding stopped and the Scottish budget to promote walking and cycling for 2012-13 was cut by 33 per cent from the previous year.

A plan by the Children's Play Advisory Service and Sport England to close residential street for several weeks for community "Street Olympics", so children could play out during the Games, was abandoned after Sport England lost responsibilities to the Department for Health.

Rob Wheway, director of Children's Play Advisory Service, said: "What we need is a real Olympic legacy of lifestyle change. Elite athletes haven't the faintest idea about a healthy lifestyle for ordinary people. As it is we'll have a [failed] legacy because people aren't joining sports clubs."

The Sport Secretary, Jeremy Hunt, said in 2010 he had "real concerns about the lack of a sporting legacy for the whole country", adding "it would be difficult to argue it was money well spent" if all we got was a few weeks of good television.

Last December the Government dumped its target of getting one million more Britons playing sport by 2013, when it became clear participation was levelling off or falling in most mainstream sports. Swimming saw the biggest drop in participation, with 435,000 fewer people taking to the pool regularly in 2010-11 than in 2007-08. Numbers also fell in tennis, football and rugby. Among those aged 16 to 19 – a key target group – overall sporting participation fell by more than 100,000 to 825,900.

A nationwide study to gauge the mood of parents and children before the Games shows nearly half of young people feel they lack opportunities to play sport at school. Half of boys feel pressured into playing mainstream sports, like football, while more than 60 per cent of girls said efforts to engage them are not working.

The Move with Mission campaign surveyed 3,000 young people and parents. Half said school sports lessons were terrible, not their thing, or boring, while a third said they still had not found a sport they liked, because too few choices were available. Tessa Jowell, shadow Olympics minister, said: "The tragedy is that what was regarded as a world-class school sports programme, copied by Australia and Canada, has been dismantled, for what most people would see as incomprehensible reasons. Why, [with] this crisis on obesity, [do we] cut the programme engaging children in healthy activity?"

Phillip Darnton, former chairman of the now-defunct Cycling England, said: "To have a legacy you need someone [in Government] to say ... what they're determined to achieve. That leadership doesn't seem to exist."

A Government spokesman said: "We have restored sport's full share of lottery funding, and with projected increases in lottery sales an extra £500m will go into sport over the next five years. Clearly, there's a lot more to do, which is why we launched the £1bn youth sport strategy earlier this year. But even in a challenging financial environment, the legacy foundations are in place."

Case studies...

'We used to have free football and rugby taster sessions – but not now'

Caroline Field, 37, a deputy head teacher and mother of three from north London, has tried to get young people in her area involved in sport. But when her school's sport partnership scheme, aimed at supporting initiatives between local schools, was cut by the council last year, the number of opportunities declined, she says

"We used to get free Bollywood dancing, football and rugby taster sessions at school, but not any more. We had people in to ensure children could do as much sport as we could fit in, but now those visits are few and far between.

"My children would rather be watching TV than jumping on a trampoline outside. We know less sport contributes to obesity. My sons play football and swim in the week. My husband takes them swimming some weekends, but it's expensive – about £10 for less than an hour."

'If there were more cycling paths, I would definitely cycle in town'

Sophie Gadd, an 18-year-old student from Surrey, is in her first year at the University of York. The city was once chosen as a "cycling city" by Cycling England, which aimed to get more people cycling, more safely and more often. But when the organisation was closed in 2011, so was the possibility of any future funding. Miss Gadd says cycling in the centre of York feels "dangerous"