The legacy of the London 2012 Olympic Games was “done down” because sport participation figures were “undercounted quite dramatically” according to the former sports and Olympics minister.

Talking at the SportsPro Live conference today (22 March), Sir Hugh Robertson said that the nature of the Active People Survey, collected by quango Sport England, rendered arguments about legacy in terms of participation “useless”.

He said that certain individuals were not counted in the survey’s measure of taking part in sport three times a week for half-hour, even when they were “training on Tuesday and playing on Saturday”.

“These people were not showing up in the participation figures because they weren’t always doing these strict three half-hours a week,” he said.

Responding to a question from Sports Management about how he would have improved the survey, Robertson criticised the fact that it was collected via landline telephone, adding: “I always used to say to people: ‘have you ever met anybody who took the survey?’ It happened to my wife a month or so ago as she was running to pick my son up from school. She said they did their utmost to persuade her that she hadn’t done her three half-hours of exercise.”

The former Conservative MP added that the number of sports participants following the Games were “undercounted, even if you look at the raw data” that revealed 1.5m more people were participating in sport.

“Actually, when I look back on my time as minister the one thing I really, really regret is we didn’t tackle the measuring system,” he said. “We’d really done ourselves down.”

The current sports minister Tracey Crouch has since altered the measuring system as one of the key points in the Sporting Future sport strategy she unveiled in December last year. Sport England will begin to collect the Active Lives Survey this year, which is more flexible and takes into account more physical activities.