Finland skipper Tim Sparv used to share digs with Walcott at the Saints and said: "Theo was very tidy. He was down to earth and kept his feet on the ground despite his success. That is what makes him a good friend.
"Did he have any bad habits? Well he watched EastEnders - which I didn't like!
"I tried to tackle him for two years in training at Southampton but I never caught him - and I'm not getting any quicker."
Sparv added: "It's going to be a hard task. We're going to have to double up on him on occasions and not leave him one-against-one because he is going to outpace anyone."
If England's kids are to have any chance of landing Euro glory for the first time since 1984, Walcott, 20, will need to be on song.
His pace can rip defences apart and Sparv, who reached the FA Youth Cup final with Walcott in 2005, added: "Everyone who watched him at Southampton knew he was a special player, with his pace and technique.
"He's so young and has done so much so I am amazed by him. But at the same time we knew he was good."