The 2012 Olympics has presented the prime minister with an opportunity to transform domestic policy over the long term, but the success of this accidental legacy is not guaranteed.

London’s Olympic bid organisers have significant ambitions for the games. To quote their promotional material: ‘grassroots participation would be boosted. An already sports-mad nation would get fitter and healthier’. To achieve this, we need to strengthen the role of sport in society and fully recognise its potential in unifying key areas of public policy.

Sport can transform communities, taking kids off the streets and getting them involved in constructive, healthy activity, thereby cutting crime and antisocial behaviour. The renewed emphasis on multisports clubs is bound up with their intended role as community hubs, promoting social inclusion and strengthening civil society. Indeed, 26 per cent of volunteers in England are sports volunteers – a fact of which Alexis de Tocqueville would heartily approve. Sport is also, of course, the ideal weapon to fight obesity, improve health and cut smoking. But perhaps most important for the government, sports policy is the perfect tool to make a direct impact on hard-to-reach, working-class communities. This factor was highlighted by the general household survey, which showed that sports participation rates among men and women who are economically inactive are 20 per cent lower than those in full-time work.

This is the opportunity, but there is a long way to go before any of it can be achieved. Our sporting infrastructure is relatively weak in the UK. Participation rates are low, largely because 70 per cent of British teenagers stop playing sport when they reach 16, compared to a drop-off rate of just 20 per cent in France. For it to leave long-term benefits, the Olympics must reverse this decline in grassroots participation and lead to a re-appraisal of the role of sport in society.

In fact, evidence from past Olympics suggests that host cities are not very good at using this elite sporting event to deliver sustained increases in grassroots participation. Australia, for example, did not see an increase in participation after the 2000 Sydney games. Their failure, along with that of most host cities, was an expectation that hosting the Olympics necessarily leaves long-term benefits.

If we are to capitalise on the opportunity that hosting an Olympics presents, we must not repeat past host cities’ mistakes. The ippr/Demos report After the Gold Rush: a Sustainable Olympics for London investigated what we can realistically expect a London games to deliver and what we would need to do to achieve this. The clear answer: plan early and embed the Olympics within much longer-term and broader strategies. We must look less for a discrete ‘Olympics effect’ than understand how the Olympics can be used to deliver on existing policy objectives.

Take increasing grassroots participation, for example. There are already clear policy aims here. The challenge is how to avoid Wimbledon-style peaks in participation (it is impossible to get on a tennis court for the two weeks of Wimbledon) and sustain the interest and excitement that an Olympics generates. This means starting now, not during or even after the games are held. New facilities are only half the issue: we will also need people, professionals and volunteers, to coach, referee and sustain people’s interest.

Three different stakeholders must act quickly to capitalise on the Olympic opportunity. First, government must maintain the recent increases in sports funding and ensure that the Olympics does not divert funding or expertise away from grassroots sport. Second, schools and local authorities across the country should mimic and extend the initiatives such as free swimming for kids that the Olympic boroughs have already established, and the Everyday Sport scheme that successfully raised participation when piloted in the north-east. Third, sports’ governing bodies should learn from the Rugby Football Union’s IMPACT strategy, the most interesting and innovative attempt to capitalise on a major sporting event (specifically the 2003 World Cup).

A lot of the legacy from a 2012 Olympics will actually be delivered before the games are held. Past cities’ failings have shown that simply expecting the 17-day event to deliver long-term increases in participation would be a tragic missed opportunity. Fully recognising the potential of sport will not only be essential to delivering on the Olympic opportunity, but will be a beneficial long-term legacy in itself. In the words of the prime minister: ‘investment is sport is about as good an investment as you can get.’