Rugby faces a dementia “epidemic” among retired professionals without serious reform of the game, the lawyer leading an action against the sport’s authorities has warned.

Richard Boardman, who is representing an initial group of seven players including 2003 England World Cup winner Steve Thompson, says doing nothing is not an option.

Thompson, 42, has been diagnosed with early onset dementia and says he has no recollection of his part in England’s glorious campaign in Australia 17 years ago.

Saints rugby director Chris Boyd said: “It’s very tragic for him that he was in a situation that he grew up in an era of rugby where the science didn’t show us about these things, really.

“I think it’s an incredibly difficult situation. They are very different environments. The cultures were very different in the clubs through that period of time, and even earlier than that.

“Culturally, the attitude towards a whole bunch of things in the world were quite different then than they are now, including in concussions.

“In the modern environment, because the science is advanced and our knowledge is advanced, I think we are very respectful of looking after head injuries, player safety and those sorts of things.

“Bone on bone training, we do two blocks of 90 seconds a week. That’s full-contact training. In the two-and-a-half years I have been here, we have had one concussion from training, which came from a back running into a prop’s hip.

“We take player safety incredibly seriously, and there are more and more protocols coming in all the time.”

A World Rugby spokesperson said: “While not commenting on speculation, World Rugby has the utmost respect for the wellbeing of all players, including our former players.

“We are unwavering in our commitment to evidence-based injury prevention strategies, and the priority area of concussion education, management and prevention, and act based on the latest available research, evidence and knowledge.”