Along with his fellow British Lions, Dallaglio was toasting the side's 2-1 Test series win against the Springboks with numerous bottles of Castle Lager in a typically noisy rugby players' party. They were still drinking well beyond 6am.
Those who were with Dallaglio that night in July 1997 remember nothing unusual about the player or the celebration. It was the sort of thing to be expected at the end of the tour, especially one that had been so successful.
But it was the alleged events of that occasion have threatened the career of England's captain and thrown into disarray the team's entire preparation for the forthcoming rugby World Cup. It is claimed that during the boisterous but apparently innocent celebrations Dallaglio and two fellow players took ecstasy and cocaine.
"We had a massive party - an all-day party," he is alleged to have said. "And half-way through the party one of the players came over to me with three Es and just popped one straight into my mouth. We dropped an E and then a couple of wraps of coke and we celebrated winning the Test series. We woke up as the sun was coming up over Johannesburg."
If Dallaglio, 26, did indeed say as much to a News of the World reporter and if he was telling her the truth, the unanswered question remaining is whether this was a one-off indulgence or something more habitual.
Yesterday as he attended a crisis meeting with top officials of the Rugby Football Union, observers were quick to point out that the demands of today's game mean no one could operate at the highest levels if they had any serious sort of drugs habit.
"The game has completely changed," said one official. "Rugby union used to have the image of players having a pie and a pint at half-time. Now all the top clubs will use dieticians and general health advisers in addition to their coaching staff."
But the transformation of the game has also changed the position of its most high-profile players. While the reaction of most involved in the sport to what has happened to Dallaglio - a player at the forefront of efforts to promote the game to children - has been one of complete surprise, it is also true that there is perhaps no rugby player more likely to find himself the subject of the tabloid scrutiny.
Dallaglio, born in Shepherd's Bush, west London, of Anglo-Italian parents, first began playing rugby at Ampleforth - the Benedictine public school in North Yorkshire.
However, the dedication required to make it at the highest level only followed the death of his sister, Francesca - a model and promising ballet dancer - in the Marchioness pleasure-boat disaster on the Thames in 1989 in which 51 people drowned.
Much has been made of the psychological impact on the young Dallaglio of his sister's death. "I was in a whole state of complete disrepair for quite a long period of time," he has said.
Coming just 10 days after his 17th birthday, the tragedy led to him leaving Ampleforth, having an unsuccessful stint at a tutorial college in Oxford and then being unemployed.
He has described this period as, "generally of no fixed abode and not doing a great deal ... just bumming around". If the allegations of drug- dealing are proved to be true, it would have happened during this time. Later, he went to study urban estate management at Kingston University.
The Marchioness tragedy also gives an insight into the kind of social scene he was mixing in, even at such an age. The boat was carrying 130 guests for a 26th birthday party, and Dallaglio would have joined his sister on board had a bout of flu not kept him at home.
The party was a typically "yuppie" event of the late '80s involving some of the brightest up-and-coming stars of the fashion and advertising scenes, and was an unashamed expression of their champagne lifestyle. Was this the kind of social life he continued with during his years of "disrepair"?
What definitely sustained him during this time was his involvement in Wasps under-18 rugby team, where he found a focus for his life and a relief from emotional turmoil.
It was not long before his talents were recognised at a national level - with him playing for every England side from under-18 level to the Sevens team. He gained his first full cap in November 1995 - coming on as a substitute against South Africa. Within two years he was made captain and now, with various endorsement contracts, he earns up to pounds 400,000 a year. But the rise has been accompanied by the attendant attention.
For a sport that has recently turned professional, and needs good publicity for its stars, Dallaglio is one of the obvious people on which to focus promotions and media attention. "He is the England captain and the fact that this is the World Cup year makes this whole thing more important," said John Holmes, an agent who used to represent the former England skipper Will Carling. "But his profile is still nothing like as high as that of the professional footballers."
After the events of the last two days, that no longer appears to be the case.
`If there were any drugs taken on the Lions tour two years ago when I was manager I was totally unaware of it'
Fran Cotton, tour manager
Eileen Dallaglio, his mother, said claims were `a complete tissue of lies'
`Every quote in there was on tape. There are four hours of tape and they are in context, and I am sure that the rugby union people will let you know that in time'
Phil Hall, editor, News of the World
Jeff Probyn, former England international, called for Dallaglio to be banned from sport if the allegations were proved. Punishment should be `very draconian'Reuse content