Chris Robshaw has hailed the impact made by England's young generation as preparations continue for a two-Test Argentina tour.
Former England captain Robshaw will be among the senior campaigners heading to South America next weekend, with the Pumas awaiting in San Juan and Santa Fe.
Despite losing a number of players to British & Irish Lions business in New Zealand this summer, England head coach Eddie Jones can still summon experienced figures like Robshaw, Dylan Hartley, Joe Launchbury, Mike Brown, Danny Care and George Ford.
But there will also be a sprinkling of youth, including twins Tom and Ben Curry, in addition to their fellow teenagers Joe Cokanasiga and Nick Isiekwe.
And another newcomer, Saracens wing Nathan Earle, underlined his talent by scoring a brilliant try during England's 28-14 victory over the Barbarians at Twickenham on Sunday.
"I have been really impressed with everyone, whether they have been 18 or 32 or something like that," Harlequins star Robshaw said.
"It was a first hit-out for a lot of guys in an England shirt, and sometimes that can be a bit overwhelming, especially being at Twickenham in front of a good crowd against a star-studded team.
"But it was perfect preparation for us going to Argentina.
"Two weeks ago it made me feel old when I looked around, and I must have been the oldest player by about seven years!
"It keeps you on your toes, I tell you that. There are about three or four of them [teenagers] in the squad now.
"They are extremely energetic, they want to get involved and they want to learn. That's the important thing. They want to soak up information, whether it is from players or coaches, and they want to improve and really enjoy the set-up.
"I think everyone has come in and done themselves proud."
England's clash with the Barbarians was their first since seeing their Six Nations Grand Slam hopes ended by defeat to Ireland in March.
Robshaw said: "It is about trying to kick on from that Ireland game, because obviously that didn't go to plan.
"You never want to lose two games on the bounce, and that was an important message for us going into it [Barbarians match]."
Hong Kong-born Earle, meanwhile, has underlined how he wants to challenge for a Test start in Argentina, where England's degree of difficulty will be considerable, given their absentees and the Pumas' strong home record.
"Eddie has said to me to just back myself and just play my rugby," Earle said. "He has been really good and filled me full on confidence. He has been brilliant.
"It was a massive surprise to even be considered, but then to actually be picked [against the Barbarians], I wasn't expecting it.
"It massively helps me being at Saracens. I kind of had an idea of what to expect because everyone had kind of briefed me, and you have an idea of what you are involved in and how you are expected to act and train.
"It was good to get a head-start, although you don't really know until you do it.
"I want to get capped -- that's the dream -- and I want to get capped as many times as possible, so it's about taking on board my work-ons from Eddie."