Let us rewind the Six Nations clock for a minute.

Or, rather, for 278 minutes. It stops at 14.36 on the afternoon of 2 February, the very moment when Brian O'Driscoll drifted through the Wales defence at the Millennium Stadium to score Ireland's third try in the match that opened this year's RBS 6 Nations Championship.

There's not much to do in Cardiff at that time of the day. Because if there had been a half-decent alternative on offer in the Welsh capital then most of the Wales crowd would have walked out right then. Not to put too fine a point on it, their side were a total shambles, being hammered at home by an Irish team that had a couple of inspired individuals in its ranks, but not a great deal more.

But then something happened. Maybe it was a subtle shift in the gravitational force deep in the hills where they used to hew Welsh coal. Maybe some stars lined up propitiously in an outer galaxy. If anyone actually knew for sure they could make a fortune selling the secret. For at 14.36 on that day Wales decided they were going to start playing rugby again. They dominated the rest of the game, scored three tries of their own, and turned a humiliating 3-30 deficit into an honourable 22-30 defeat.

But for context, we should look even further back. Wales, astonishingly, came into this year's tournament on a run of eight consecutive defeats, just two short of their worst run ever. They had been beaten at home four times on the trot in an autumn whitewash. Historically, Welsh rugby has always lurched between glory and crisis, and there was no question that they were firmly at the wrong end of that spectrum at the start of this Six Nations.

And now? Licking their lips with glee at the prospect of taking on England in Cardiff next weekend. Wales would have to overcome a points difference that is teasingly short – after England's faltering display against Italy yesterday – of Snowdonian proportions to actually win the title, but the thought of derailing an English Grand Slam attempt is an exquisite enough notion to the Welsh. If they can pull it off then the men in red shirts would scarcely cement themselves more firmly in the nation's affections if they went out and won the World Cup as well.

'We can trace almost all the disasters of English history to the influence of Wales' wrote Evelyn Waugh in Decline and Fall. He was probably pushing it a bit with that statement, but a fair few English rugby disasters can certainly be laid at the door of the men in red shirts.

We in Scotland share the fond memory of that Scott Gibbs try in 1999 that put a stick through the spokes of the English chariot and gave the last Five Nations title to us, but Wales had been doing that kind of thing for years. Between 1963 and 1991 England did not achieve a single victory on Welsh soil.

But let's go back to those 278 minutes – the precise amount of time Wales have now played without conceding a try. It is a figure that speaks of an astonishing level of defensive resolve, application, organisation and effort. There was a time when Welsh players treated defence as a kind of irksome chore – and a pretty pointless one, too, when they backed themselves to score more tries than the opposition anyway.

"I've been pretty pleased with the defence," said Shaun Edwards, the Wales defence coach. "The first half against Ireland was very unlike us, but since then we have been well led by Jamie Roberts.

"The ratio of tackles to how many times we turned the ball over was exceedingly high. Our post-tackle work was excellent. That goal-line stance at the end with 14 men with everything defence coach would want. It's always critical in big games. Defence wins championships."

It might also win places on this summer's tour to Australia. All the sub-plot of Saturday's match at Murrayfield revolved around head-to-head match-ups between Scottish and Welsh players. Would Stuart Hogg steal a march on Leigh Halfpenny? What about Tim Visser against George North? Euan Murray and Adam Jones? Kelly Brown versus Sam Warburton?

Even when the scoreline was close, there was a powerful impression that the men in the red corner had the better of every one of those contests.If one moment summed up the match better than any other it was in that passage in the first half when Hogg sent the ball skywards, raced after it, only to arrive just a fraction of a second after Halfpenny had plucked the thing out of the air and started sprinting towards Scotland's half.

On short rations, North ran more dangerously than Visser. The scrums might have been a gruesome spectacle, but Wales won the decisive ones and that means another tour for Jones the prop. Ospreys lock Alun Wyn Jones may have dynamited Jim Hamilton's prospects of making the trip as the boilerhouse bruiser. And if Warburton did not knock Brown out of the equation – if he goes, the Scot is more likely to be used on the blindside flank – his magisterial performance may just have given him the Lions captaincy as well as a guaranteed slot in the Test side.

Warren Gatland will have no problem stacking his squad with Welsh players. He knows them inside out, knows what makes them tick. Wales might not reach the heights of the 1977 Lions tour to New Zealand, when they provided 17 players to the squad, but they have unquestionably booked a few places already. And Scotland, yet again, could be struggling to make up numbers.