The Arsenal winger was the surprise exclusion from the World Cup squad last year - four years after being Sven-Goran Eriksson's shock inclusion - and admitted that manner of the shun had left him angry, numb and confused.
He said: 'On the day the squad was announced, I went to Brocket Hall, the country hotel near my home in Hertfordshire, for a last round of golf before going to South Africa.
Scary: Theo Walcott has lifted the lid on his relationship with Fabio Capello
'I was on the fairway on the fourth hole when Mr Capello rang me on my mobile. He was short and to the point. He said he was sorry but I hadn't made the squad and I wouldn't be going to the World Cup.
'I was stunned. I had a bit of a cry. I respected Mr Capello's decision but I went through a whole mix of emotions in just a few days - I was numb, shocked, upset, angry, confused.'
Yet Walcott says deep down he knew he had disappointed Capello with his attitude in and out of training.
In his new book, Growing Up Fast, which is being serialised in The Sun, the 22-year-old discussed a raft of incidents in which he was left humiliated by the England boss.
'Before the World Cup we headed out to a training camp in the Austrian Alps before we left for South Africa. Something happened out there that shook my confidence.
Making progress: Walcott was the surprise exclusion from the World Cup squad
'It was the second day, and I made a run inside from my position out wide on the right. Suddenly Mr Capello started screaming at me at the top of his voice. Training stopped and everyone stared at their feet and looked embarrassed.
'"Theo," he was yelling. "I will kill you if you come inside like that again." Despite Mr Capello's outburst, I never quite knew what was required of me. I was confused.
'I had been injured so much that season that my confidence was fragile, but no one ever helped me. If you are the boss, surely you want everyone playing well and you want to encourage everyone. It killed me and I felt it wasn't fair.
'On an earlier occasion I was woken by the phone ringing in my hotel room at The Grove - the England team's Hertfordshire training base for home games. It was one of the England staff and he sounded nervous. He said I'd missed a team meeting and that I'd better come and sort it out with Mr Capello.
'I'd thought the meeting was at 7.30pm but it turned out it had been half an hour earlier. I'd had an afternoon nap, set my alarm too late and slept through the meeting. I could feel my heart thumping. I had never missed a team meeting before. I was in trouble.
'I stood in front of his door for a few seconds, my heart thumping. I knocked and there was a brief wait that seemed like a lifetime. Then Mr Capello opened the door. He stood there, looking at me.
'"Boss," I said, "I'm so sorry I missed the meeting. I misread the time."'
Mr Capello's expression stayed the same. He shrugged his shoulders, then let the door swing shut in my face. He hadn't said a word.
Confidence: Walcott had a tough time with injuries last season
'"Oh, f*** me," I thought. It was much worse than getting a severe bollocking. It was seriously scary.'
'Emile Heskey fell foul of him during the World Cup qualifiers when Mr Capello caught him texting someone during dinner. He got up, yelled and chucked something at him.'
However in the aftermath of the World Cup farce, Walcott has revealed that things are very different now, and backed them to continue to do the same.
Back in the fold: The Arsenal man has earned his place back in the international set-up
'The atmosphere with England is much more relaxed now. There are more smiles around the camp these days. Mr Capello has changed, lots of things have changed. He is more approachable.'
And looking to the future, in which Walcott hopes to be part of many more World Cups, he believes Wayne Rooney will one day become England captain.
'One of the best mixers, one of the people who moved easily between the cliques, is Wayne Rooney,' he added. 'He's such an easy bloke to get along with and he's popular with everybody. In the future I think he'll make a great England captain.
'The other thing about him is that he always wants to win. Always. A few days after we arrived in Germany for the 2006 World Cup, I walked past the snooker room in the hotel and Wayne was having a match with John Terry.
'It was close but when JT sank the winning pot, Wayne lost his rag and snapped the cue with his hands. It put the fear of God into me.'
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