Rugby: England hooker Steve Thompson among eight former players with early onset dementia starting a claim against rugby unions

Steve Thompson celebrates beating the All Blacks in 2003. Photosport

Former England hooker Steve Thompson says he can't remember winning the 2003 Rugby World Cup as he battles early signs of dementia.

Thompson, 42, is one of eight former players starting a claim against the game's authorities for negligence, the BBC and Guardian reports. All of the players are under 45.

The BBC and the Guardian are reporting the former players have sent a letter to the governing bodies for English and Welsh rugby and World Rugby. With a possible group class action to follow.

As first reported by the Herald, 70 former rugby players could have contributed to the action, including multiple All Blacks.

Thompson said due to repeated head knocks in his career, he can't remember test matches including the World Cup in 2003.

"I can't remember any of those games. It's frightening," he told the BBC.

"It's like I'm watching the game with England playing and I can see me there - but I wasn't there, because it's not me," he said.

"It's just bizarre. People talk about stories, and since the World Cup I've talked to the lads that were there, and you pick up stories, and then you can talk about it, but it's not me being there, it's not me doing it, because it's just gone."

It echoes the words of former Waikato representative and Junior All Black John "JJ" Williams who can't remember the day he got married.

The 63-year-old also can't even remember anything from his playing days in the late 1970s and early 1980s.

He suffered many concussions during his short career and has been told he is likely living with the degenerative brain disease chronic traumatic encephalopathy (CTE).

"All those years, I don't even remember the day I got married or my career. It's like another life that existed that I didn't know about," Williams said.

Williams is speaking out after the Herald revealed a lawsuit is being prepared overseas, covering former players left with cognitive issues ranging from post-concussion syndrome to suspected CTE.

As many as 70 former rugby players could have contributed to the action, including multiple All Blacks, whose lives and livelihoods have been affected by cognitive impairment.

Williams' lawyer has contacted a QC in London about the action, but he doesn't yet know the ins and outs of the situation.

He was the first New Zealand rugby player to publicly commit his brain to science after being diagnosed with CTE.

The concussion issue is something close to his heart for Williams, who urges anyone with brain problems to seek help.

He lives with constant headaches, is sensitive to light, has mood swings, has blackouts, and often forgets what he is doing.

The state of his mind affected his marriage, which has ended, and his work life. He is cared for at all times by his new partner.

Head knocks weren't on anyone's radar when Williams used to lace up the boots but he doesn't begrudge the lack of action, "it's how it was".

He recalls being knocked out during a game and continuing to play until about a month later when doctors discovered he had fractured his skull.

"Everybody got a bit of water and carried on," he said. "There was no such thing as replacements like there is now. That was just life."

He was forced to give up life as a stock agent, forgetting things like which farmer to go and visit or what weights to tell them.

"Then I went farming and I'd go and get the cows and my parents would see there was no one at the shed," Williams said.

"I'd be in the paddock, sitting there if something went wrong like if there was a sick cow or something not right, I'd freak out and sit there.

"I don't know what I did. My parents didn't know what the matter was, nobody sort of knew."

The only stuff he knows about his own rugby career is through newspaper clippings his mother left for him.

"I feel embarrassed about what happened to me and the trouble I caused from all of that. At the time, you just can't explain it," Williams said.

However, he says a great weight was lifted off his shoulders after tests by a neuro-psychologist indicated he had CTE.

CTE can only be definitively diagnosed post-mortem so Williams has notified his family that he wants to donate his brain for testing.

"It's a hell of a relief [once you know]," Williams said.

"There must be hundreds of blokes out there who are going through this, the same trouble that they don't know why. They should go and talk to somebody about it."

Two former All Blacks, Carl Hayman and Geoff Old, told the Herald they have been in contact with British-based lawyers about their post-playing medical conditions.

"From what I understand, it's a pretty ever-growing list of [players]. I think it's going to be something quite substantial that's going to come from it," said Hayman, a 45-test tighthead prop.

Hayman, 41, said he was contacted and offered scans and tests to ascertain the damage he'd suffered over the course of a career where he played in New Zealand, England and France. He declined the offer to undergo testing.

The action is being readied by lawyers in Britain and will likely target several national rugby bodies within that jurisdiction. Herald sources indicate it will argue that rugby authorities have known about, and subsequently underplayed, the risks associated with repetitive head injuries for decades.