Scotland coach Ian McGeechan believes forward Simon Taylor has surpassed the level of fitness he enjoyed even before his hand injury in November.
Taylor broke his left hand in the Test against Australia and has been forced to sit out the two opening Six Nations games before his inclusion in the squad to face England.
The 21-year-old has enjoyed a tremendous two days after being named in a provisional British Lions squad for the summer.
But McGeechan has no doubt that the Edinburgh Reivers number eight, who replaces Jason White, is back to his best.
McGeechan said: "I’m very pleased with the way Simon has come back having had the hand injury.
"I know he has been working hard so he is fitter, faster and stronger than he was in the autumn.
"Simon has been supervised and watched very closely and he can do many things now.
"He has played very well in the A team and is back to the level he was at when he got injured."
But McGeechan admitted that informing White of the decision to drop him in favour of Taylor came with much soul searching.
White was outstanding on his international debut in the win over England last April and was included in the squad against France and Wales this year.
But McGeechan conceded that balance had been the key to his decision.
McGeechan said: "I admit that it was one of the hardest phone calls I had to make last night.
"Jason is superb as a squad member and it was purely a matter of balance of what we want to try and do.
"There was a lot of discussion around it and, because of the way he is and the way he has been involved - his attitude is superb and has been excellent in his support in the first two games - those are difficult decisions."
However, McGeechan believes that the Calcutta Cup game is still a step too far for full-back Glenn Metcalfe.
The Glasgow Caledonians man returned to the international stage in the A team game against Wales last week after a long-term knee injury.
But McGeechan will not take a risk on Metcalfe, or stand-off Gregor Townsend, for the game at Twickenham.
McGeechan said: "The danger is over doing it too early. He (Metcalfe) just needs that extra time because he is an explosive player."
But McGeechan insists that the challenge of playing at Twickenham will bring out the best in his squad a week on Saturday.
"England are throwing the gauntlet down and are playing very well. They are a good side and the challenge is massive for us.
"They are the sort of challenges you live for - you want to be playing against the best as often as possible and England are one of the best.
"It is important that we keep moving our own game forward as a squad and stay very competitive in every environment we are in.
"So a win at Twickenham would be a massive boost for us. It would be huge."