Ahmed, 18, became the youngest man to play Test cricket for England in December when selected during the Pakistan series and marked his debut with a stunning five-wicket haul in Karachi.
The confidence of the Leicestershire allrounder has been clear from the outset despite his tender age, but even he conceded his call-up to the group for the second Test on Friday was unexpected despite injury concerns over Moeen Ali.
"It means everything. I would never have dreamed this," Ahmed told England's official Twitter account.
"To be part of an Ashes squad at my age, at Lord's as well, I never saw it coming so it is lovely to be a part of.
"I was actually with my brother when Baz (head coach Brendon McCullum) called me, but my mum and dad found out straight away, and a couple of my friends.
"Baz said I would be joining up with the squad for the next couple of games, well the next four games. Yeah, he was so chilled about it as well but I was on the phone a bit panicky but just happy."
Ahmed joined the group on Sunday and had his first nets session at Lord's a day later.
While Ahmed has never played at the home of cricket, he is familiar with the ground having bowled there to future captain Ben Stokes when he was 11 and impressed the late Shane Warne two years later with his leg-spin.
He added: "Lord's is always a special ground.
"I've never played here before, I've not been on the main pitch either but (I have) good memories from when I was 13, 14 and I net bowled for England as well."
Quizzed on his Ashes memories, Ahmed admitted the first time he fully watched five days of a Test against Australia was the thrilling opener at Edgbaston last week.
With Moeen able to bowl during Monday's training session, Ahmed is not expected to feature at Lord's but made no secret of how much he relishes being part of the environment Stokes and McCullum have created.
"The last game was probably the first time I watched the full Ashes, the full days," Ahmed revealed.
"I was playing a game against Notts for Leicestershire and I was getting drinks every two overs for the score. The last game was unbelievable.
"Baz gave me a call on Friday morning. He basically told me I would come in and join the lads. It was unbelievable.
"I love it. I love being around this new environment that's been created. It is unbelievable."
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