There was a bizarre but possibly telling exchange towards the end of Vern Cotter's media briefing at Twickenham on Saturday evening.

The Scotland coach had been asked a straightforward and innocuous question about how many of his eight replacements were due to injuries and how many were merely tactical. Cotter thought for a few moments, looked blank for a few more, and then replied.

"They were all injured," he said. "All of those who came off were injured, yeah."

The questioner tried another tack. How many were now doubts for next weekend's clash with Ireland?

"All of them," Cotter responded.

So he could have eight players unavailable?

"Absolutely."

If we discount the possibility that Scotland's attrition rate was on a scale more often associated with a motorway pile-up, Cotter's answers made no sense whatsoever. There might have been an element of graveyard humour about them, but his body language said something else. The simplest explanation was that he had simply run out of answers. And possibly in more ways than one.

It is a too-familiar trajectory for those who take on the job of coaching Scotland's national side. The reign begins with buoyancy and optimism, with players proclaiming that they have been energised by the new arrival, with powerful signals that a bright new dawn is on the horizon. But as that golden sun fails to rise and the defeats pile up, initial frustrations give way to something closer to despair and a sense of resignation.

Cotter might not be there yet, but there was a clear weariness about him after this match. He was the hottest coaching property in Europe when he agreed terms with the SRU two years ago, but he is now on the cusp of matching the achievement of his fellow Antipodean Matt Williams by leading Scotland to a Six Nations whitewash in his first season in charge.

It is not a comparison he will relish, and nor is it one that should be drawn at this stage. Williams' teams played in the wayward and directionless manner you would expect under the tutelage of a coach who was big on mumbo-jumbo but rather less adept at fashioning a half-decent gameplan. Under Cotter, Scotland have played with pace and purpose and they have unquestionably improved, but if self-belief is the last piece of the jigsaw it will more easily be acquired if they can deal with the pesky business of scoring more points than the opposition.

They managed to do that in the first half of this match, but for the second time in this tournament they failed to add to their haul after the interval. In recent seasons, Scotland have built a reputation as strong finishers, so it is a worrying trend. There is no suggestion that fitness has been an issue, but you do wonder if other sides spend the first 40 minutes figuring out how to stop Scotland, and the second putting the plan into action.

This match provided a lot of evidence to support that theory. Scotland started woefully, almost conceding a try in the first play and then coughing one up after only four minutes, but for 25 minutes before the break they played some wonderful rugby. They dazzled their fans and bamboozled their opponents as they whipped the ball down the line and kept shifting the point of attack. There was no question they were worth their 13-10 lead at the break.

But then things went badly awry. George Ford, the England fly-half who had a wonderful game, sold the Scottish defence a dummy three minutes into the second period and skipped through the gap he created to score.

Emboldened, England began to pile on the pressure, pinning the Scots back in their own half. The points wer not exactly flowing, but England had extinguished Scotland as an attacking threat, and they duly closed out the game when Jack Nowell collected his late try in the left corner when, for the second game in succession, Scotland failed to tidy up after a penalty attempt had rattled back off a post.

A thrilling finish to the championship now lies in store next Saturday, as England, Ireland and Wales set off on a points chase. Scotland have no loftier aim than to avoid a clean sweep of defeats when they host the Irish at Murrayfield. The odds against them doing that are daunting as they have slid from eighth to 10th place in the world rankings over the course of this championship, while Ireland, despite their loss to Wales, have been rated the third-best side on earth for the past few weeks.

"We take it on the chin but I think there is improvement," said Cotter of this result. "We just have to keep working that way, analysing and shifting forward. I thought there was a massive shift in our game, but we need to keep moving. Ireland beat England so it will be really tough for us next week.

"If we can repeat and develop parts of our game that we did well under pressure we will start believing that. I am encouraged, I really am. I'm frustrated we haven't got the win, but we are working towards it."

Maybe so, but this has been a brutal championship for Scotland. They have gone forward on the pitch, but backward on the scoreboard. They have a fierce build-up schedule for this year's World Cup. It is wins they now need, not performances.