Rugby can be a tough game to play and, occasionally, a desperately tough subject to write about. Particularly when painful truths are being starkly outlined by the most honest, respected and outwardly resilient of men. And by individuals who, having lifted the 2003 Rugby Rugby World Cup, have enjoyed the ultimate professional high the sport has to offer.

There was precious little to celebrate, sadly, when Phil Vickery popped around for a sitdown chat with his old England front-row pal Steve Thompson as part of a new documentary, Unbreakable: England 2003, released on TNT Sport this week. In a perfect world it would have been an excuse for warm reminiscences and fond memories, a reunion as sweet as the old chariot itself.

Related: The Breakdown | From Jonny to the Fun Bus – lessons from England’s 2003 World Cup heroes

Instead it yielded one of the most sobering pieces of footage imaginable. Thompson, 46, can no longer remember anything about winning the World Cup having been diagnosed with early-onset dementia in 2020. He told his teammate about his suicidal feelings and of thinking it would be less hassle for everyone else if he was no longer around. Vickery placed a reassuring hand on his friend’s knee before softly sharing his own issues. “Someone said the other day ‘You know what you signed up to.’ I said, ‘Yeah, I know what I signed up to but I didn’t sign up to being brain damaged.’”

Vickery, 48, is also among the retired players with neurological concerns who have joined the legal case against the sport’s governing bodies. As he puts it “a bit of my brain is dead that shouldn’t be dead” and the future is uncertain. “I’m not angry, I don’t blame anybody, we did what we did,” he says, making the unimaginable sound almost matter of fact. “I do worry about the future but I live life a little bit now. Try and do things which make little memories now rather than waiting further down the road.”

With a divorce and bankruptcy to cope with as well, the sporting fame Vickery worked so many years to achieve is exacting a heavy price. As Thompson says, players from that era – the early days of professionalism – seldom paused to consider whether rugby would eventually catch up with them, beyond the risks of arthritis and stiffening joints in their dotage. “The way I look at it that was our job at the time,” says Thompson, trying hard to keep his emotions in check. “We got asked to do that and you do it to the best of your ability. You don’t question anything around it. That’s probably why we got as good as we did.”

The heart continues to bleed for them both. These were the unselfish yeomanry who carried England home, a key part of the foundations upon which so much else was built. And yet did the game of rugby care enough for them? Also included in the film is a conversation between Vickery and another of the boys of 2003, Lewis Moody. Both subsequently captained England, both put their bodies on the line to an unhealthy degree. When asked how many times he was knocked out playing rugby Moody replies: “Boatloads”. Vickery could remember it happening 20-30 times to the former Leicester flanker and those were just on the occasions when he was present. “Of course in hindsight there are things we’d do differently,” replies Moody, quietly.

Maybe, as Moody went on to suggest, it is partly an old-school male thing. Don’t complain, show no weakness, get on with it, stiff upper lip. When the gladiators of 2003 met up again for a 20-year reunion, it quickly became apparent not everyone had flourished in the intervening years. Carving out a fresh identity in the real world and adjusting to life outside the dressing-room has proved harder for some than winning scrums, nailing lineout throws and kicking drop goals. It has led to the launch of the 03 Champions initiative in a concerted bid to help the next generation of retired players.

But the more you think about it, the more you wonder if top-level rugby is normalising stuff, both physical and mental, well beyond the outer limits of healthy sporting resilience. On the first page of his recent straight-shooting autobiography View From The Second Row, the World Cup-winning forward and former All Black captain Sam Whitelock details the alarming litany of injuries he has had from rugby down the years. “Scrum toe, a broken little toe, multiple ankle and high-ankle sprains, a broken ankle and torn ankle tendons, a torn Achilles tendon, twice, torn calf muscles, a partial tear of a posterior cruciate ligament, a pulled quadricep, a pulled hamstring, a torn adductor, a sports hernia, snapping hip syndrome, multiple cracked ribs, broken fingers, thumb and hand, hyperextended fingers, torn ligaments in a wrist, hyperextended elbows, a torn labrum in the left shoulder, disc bulges and stress fractures in the thoracic spine, infected wisdom teeth, multiple broken noses, a blot clot in my nasal passage, multiple cuts on my brow and head, an eyelid sliced open, a hole torn in my ear and multiple concussions and delayed concussions.” Along the way he has also had had five surgeries under general anaesthetic. This, remember, is one of the lucky few who quit at a time of his own choosing.

And so it goes on. Just last week, in case you missed it, the Cardiff back-row forward Shane Lewis-Hughes had a finger amputated in order to prolong his career. He hopes to be back playing within a month. All part of a tough old trade? Do not believe anybody who tries to tell you the modern game is going soft.

But, equally, it cannot simply be left to sympathetic wives, partners, friends and ex-colleagues to pick up the pieces once the Friday night lights have dimmed and the game’s darker consequences are exposed. The sport needs to do much more for its battered infantry – and soon. In the meantime here’s to Phil, Steve and Lewis and every other member of the 2003 squad going through tough times. And to those less celebrated former players whose stories are not yet told. We’re all with you.

• Unbreakable: England 2003 premieres on TNT Sports on 11 December.

• This is an extract taken from our weekly rugby union email, the Breakdown. To sign up, just visit this page and follow the instructions.