There was sleet falling outside at The Oval, where England celebrated a famous Ashes series victory in September, but indoors a new generation of cricketers were at work.
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One young bowler was already impressed that a few words from Andrew Caddick had helped him change his angle of approach to gain more consistent out-swing.
In another corner, Mark Butcher was impersonating other famous left-handers as he demonstrated the importance of keeping the head still during the bowler's run-up.
Saeed Anwar's trigger movement and Brian Lara's flourish with the bat both come into the tutorial.
Butcher knows how much of an impact a famous player can have on a young career as he treasures a meeting with West Indies great Larry Gomes when he was eight years old.
"I used to love watching him play - he was a left-hander like me," Butcher told BBC Sport.
"I got to meet him at a charity match and he spent half an hour chatting to be about batting and it's something I'll always remember.
"Cricket has always been in my blood but other people don't always have that sort of immediate connection so that's why this is important."
Fellow coach Mark Ramprakash, who came through Middlesex age-group teams, recalled: "I met Mike Gatting at the age of 15 and that was a great inspiration to me.
"That's why it's very important that former players and current players meet people and give a bit of encouragement."
"The whole idea is to see if we can unearth a bit of talent and give a taste of what it's like to have a life in cricket"
The ACE Cricket Academy, fronted by Northants batsman Usman Afzaal, attracted more than 100 aspiring cricketers, mostly in their teens, to South London.
Coaches Caddick, Butcher, Ramprakash, Afzaal, Chris Lewis, Alex Tudor and David Capel boast 244 Test caps, with 9,290 runs and 396 wickets.
Similar development days are taking place in the next two months at Trent Bridge and Old Trafford and the academy is running further courses into the summer.
Afzaal is keen to stress he does not see the venture as a rival to the established order but the presence of big names is clearly a draw.
"I don't think there's anything wrong with [the county development] system," said Afzaal.
"But when we did our clinic last time we had such a volume of people it would have been silly not to do it again."
Butcher is captain of a Surrey club that has a widely-praised youth set-up but admitted: "It's always possible that people are going to slip through the net.
"You can't have a system that's perfect but the main thing is to get people to come out and have a go. If they do that you never know what you might find.
"The whole idea is to see if we can unearth a bit of talent and give the youngsters a bit of a taste of what it's like to have a life in cricket."
"First of all they have to have a passion for the game - that means they don't look upon playing it as hard work"
Meanwhile, Lewis and Worcestershire seamer Nadeem Malik, who signed a professional contract after taking part in an ACE programme, fielded questions on life as a professional.
Ramprakash's advice was simple: "First of all they have to have a passion for the game.
"That means they don't look upon playing it as hard work or that someone else has to drag them out to practice.
"They have to be dragging their mum and dad to give them a lift to the ground."
Caddick was realistic about the chances of many of the players, but keen to leave them with one message.
"A lot of these guys won't get to international or first-class level," he said.
"But if they get to a level they enjoy that's the main thing."