Barry said: "Martin O'Neill has been very good to me. One of the first things he said to me when he arrived at Villa 14 months ago was 'if you stay here with me, you'll improve a player and you'll eventually get your England call-up again'.
"At that time, I was facing a big decision, whether to try moving to a new club, whether it would be good for my career.
"But when I heard Martin O'Neill was arriving, that got me thinking straight away, even before I spoke to him, that it maybe best for me to stay around and that has been the case."
Barry was a left-sided centre-back when chosen for the Euro 2000 squad under Kevin Keegan, then switched to left-back and onto the left-sided midfield slot before O'Neill shifted him into the middle of the park.
He said: "We were 1-0 down at half time to Everton when I first got a chance in the middle. The manager changed it around then, we finished the game quite strongly and since then I've stayed there.
"In the central midfield position, you are in the thick of the action. Passing is a big part of my game and in central midfield you can express yourself a bit more.
"I've been pushed about the park for years so I didn't get nervous about playing a new position. The fact I'd played 30-40 games there at Villa meant there were no nerves in the Euro games last month."
Barry recognises the experience and class that Lampard and Steven Gerrard possess and he is just happy to be in the shake-up to face Estonia at Wembley on Saturday.
He said: "At this moment, it is great just being talked about playing for your country. These are big games and, if selected, I feel I can do the same job again.
"But when you come in here, you meet up with great players who have got more experience of playing for England than me. I wouldn't say there is a big rivalry.
"But I do feel I am playing as well as I ever have."