Not until the last of the video referee's five, second-half adjudications on Tongan try attempts had been made, with the timekeeper's final hooter having blown, could he, his 11 remaining on-field colleagues and their supporters start to celebrate a 26-24 triumph which truly fitted that description.
Scotland had spent the 80 minutes being battered ferociously by much bigger men and, as he sat down beside Steve McCormack, Scotland's head coach, Brough knew he was facing a roomful of people who had given them no chance.
"A few of you didn't know each other [before the tournament began] and the team you beat tonight were probably fourth favourites in the tournament. Can you say a few words about what it's like to have this side come together?" asked an Australian journalist.
In replying there was maybe just a hint of a dig from Brough - a player overlooked by the England selectors - who has now led the only one of the Home Unions to claim a first-round victory. However, his main thrust was that this is a Scotland squad feeding off a down-to-earth sense of collectiveness.
"It's always a mix when you get the [Australian] NRL players, the Super League players and the National League players and when we all come together we couldn't have done it better," he responded. "We've had one drink of beer together and the rest of the time we've been knocking about together, playing cards together and the spirit of that has helped us today. In our camp there's nobody better than nobody else. Everybody can put in their two pence and Steve will listen to it, but at the end of the day Steve calls what goes on and that's what's helped the group today."
As he demonstrated under further interrogation, Brough is acutely aware of the importance of this result both for the World Cup in terms of generating real doubt as to at least some pool outcomes and for the sport in general as it bids to extend its reach beyond its heartlands.
"Any thoughts about Italy, Danny?" asked an English reporter. "Not long ago not many people would have thought that Scotland v Italy would be such a massive game."
The reply was accompanied by a wicked grin.
"I have got a thought on Italy . . . I think they've got 15 or so NRL players but coming here just shows 'owt can happen on its day. We have to learn from today and we'll have to be better if we're going to beat Italy, but we've got the win. They'll probably be the favourites but isn't everybody when they play Scotland," said Brough.
If this was not quite the equivalent of North Korea's footballing triumph over Italy in 1966, a fairer comparison might be with what was then Western Samoa's surprise win over co-hosts Wales at rugby union's 1991 tournament. That was the result which signalled how rugby union was changing, shifting onfield power at least away from the traditional powers and, since unpredictability is the lifeblood of sporting competition, Scotland may have provided a much-needed transfusion for rugby league.
Tuesday's match was a pulsating, captivating encounter which ebbed and flowed in remarkable fashion.
In the first few minutes, before Tonga opened the scoring, it looked as if they were simply going to pulverise physically inferior-looking opponents. Yet the frenzy of the Scottish response, hunting in packs in defence and hustling and harrying the big men when they did start getting a supply of possession, was staggering as they raced into a 20-4 half-time lead. Tonga then completely dominated for 25 minutes, scoring four fine tries and having three more turned down by the video referee as they pressed relentlessly. Yet when they finally fell behind, the Scots once again responded to reclaim the lead with eight minutes remaining and then hold out manfully thereafter.
They finished with 12 men after Kane Linnett made what proved the right decision to commit a professional foul and had to wait for that last decision by the replay official who might easily have reckoned that a Scot had illegally stripped the ball in the last play in Scotland's in-goal area.
After all of which the only arguable downside is that it has reinforced the impression that co-hosts Wales are in the much easier of the minnow pools, a point previously made on behalf of the Italians.
Pool C, in which Tonga were favourites, now looks wide open since Italy have played and won their single cross-pool tie against Wales, who now need only to beat the Cook Islands and the USA to reach the quarter-finals as the top side in Pool C.
It is now quite possible that all three teams in Pool D will claim one win in their matches against one another which could favour Scotland since they have the chance to pile up points difference in their final match, the cross-pool tie against the USA. That will not, for the moment, be concerning Brough and his men, who will only be thinking about finding a way of beating the Italians after having just achieved what they have in setting this tournament alight.
"To be fair, World Cup games are never pretty because the best players are going at each other, but we had to find a way and it was important as a group that we won this to set up our pool and this tournament for Scotland," said the captain.
For perhaps the first and last time, their leader did his men something of a disservice in saying so, because Tuesday's match was a joy to watch and those who were there surely cannot wait for Sunday's Scotland v Italy clash.