A High Court judge has ruled that an RAF officer crippled during an "It's a Knockout" style fun day is eligible for compensation, a figure which could approach £6 million.
Senior aircraftman Robert Uren, from Tehidy, was 21 when in July 2005 he suffered crippling injuries when he dived head first into a shallow ball pool at a charity event in High Wycombe.
Now paralysed, he has been fighting ever since for compensation and had been through two High Court hearings and another at the Court of Appeal before this week's judgement.
Mr Justice Foskett ruled that the Ministry of Defence and Berkshire based event organisers Corporate Leisure (UK) Ltd were liable for Mr Uren's injuries.
The judge said that the assessment of the risk posed by the apparently harmless game were "fatally flawed" and no-one had considered the risk to life and limb posed by head-first entry.
He added: "If they had been properly assessed, steps would have been taken to eradicate the real risk of serious injury that there was without in anyway spoiling the particular game or diminishing its social value or the social value of the whole afternoon.
"No-one blames Mr Uren for what happened. All he did that afternoon was the same as about half the rest of the participants in the game.
"His misfortune was that the dive executed went wrong for some reason. It could easily have happened to someone else."
Earlier Mr Uren's counsel, Sir Geoffrey Nice QC, had attached the risk assessment carried out before the event as "completely defective".
It would, he said, have been "relatively easy" for the commentator to issue safety instructions to competitors and warn them against entering the pool head first.
The game involved rival teams jumping into the pool, which was had 18 inches of water in it, to retrieve plastic fruit.
Lawyers for Corporate Leisure and the MoD fought Mr Uren's claim, insisting the game, as played, was safe.
Making his judgement, Judge Foskett concluded: "This was a responsibly organised day that, sadly, ended in a tragedy that could and should have been avoided."
The ruling opens the door for Mr Uren's to claim the £6 million his lawyers say he needs for lifelong care and assistance.