We should have won but it's a work in progress, says Borthwick
After two tries for Max Malins and one from Ellis Genge, England still led by a point with three minutes to go only for a second try by flying Scots winger Duhan van der Merwe to secure a third successive Calcutta Cup victory for the visitors.
"At 20-12 up we shouldn't have let that get away from us. We got in a position where we should have gone on and won," Borthwick said.
"I'm really pleased with the response to the setbacks in first half but really good teams wouldn’t let the opposition back in at 20-12 we are striving to become a really good team.
"You go through that pain, you don’t want to, but we'll now look at it to make sure we are better."
It was a mixed performance from England, who spent the first 15 minutes kicking the ball at every opportunity. They eventually seemed to take control but kept being caught out as the Scots hung in and then made the most of limited possession.
"There was some good stuff from the attacking side, the try- scoring potential, the game was quicker. But as you look at moments in that game, we were hit by a couple of scores that came out of nowhere really," Borthwick said. "The team reacted well and maybe if you'd rewound a bit they might not have done."
Borthwick stressed that he had had only 11 days with the squad, and, along with a new coaching team, it was always going to be a challenge to implement new ideas and systems.
"England's set piece in recent times has not been strong – the scrum and maul will take time to build and we will persevere with that," he said.
"There has got to be mistakes as you build a team and an ethos. I've asked players to do things differently and they've really embraced that. Did I see signs of improvement? Yes. We are building here and it takes a bit of time.
"But we will be back here in eight days (against Italy) as a better team."
It was the same message from captain Owen Farrell, who said there had been "massive improvement", presumably from the autumn series.
"For now, we will give credit to Scotlandk for sticking at it like they did. They played well and scored that try in the end but it never felt like we went away, we caused them some problems and we'll make sure we build on it," he said.
"The thing we were going to do, regardless of the result, was get better and we will do that. There were blips but it felt like we had good energy and were in the fight all the way through.
"The result is disappointing but we are at the start of our journey."