Walcott will always be remembered as the teenager who somehow made it into Sven Goran Eriksson's squad for Germany 2006 without playing a game for Arsenal.
The gamble did not work, since Eriksson declined the opportunity to give the then 17-year-old even a minute on the pitch, raising questions about why he had been picked in the first place.
Scorer of a memorable hat-trick in the famous 4-1 hammering of Croatia in Zagreb at the start of England's successful World Cup qualifying campaign, Walcott is a more obvious choice this time around, even though his form for the Gunners this season has been distinctly patchy.
However, Capello showed faith in Walcott for the friendly win over Egypt in March and it is widely anticipated he will be part of the 23-man squad the Italian submits to FIFA on June 1.
And, once in South Africa, Walcott is eager to prove he was worth selecting this time.
"I have been to a World Cup already and hopefully it will be a different story this time," he told Arsenal's official website.
"I was only 17 [at the 2006 Finals]. I was a baby-faced kid just enjoying the occasion. But I'm 21 now and I will try to make my mark.
"I have learned a lot since then. I had experience in the Premier League and have worked with the boss [Arsene Wenger] and the players.
"I am learning to use my pace at the right time and I know that I will be judged on my goals and assists."
Walcott has been part of a reduced 24-man England squad that has been put through their paces during the first two days of their altitude training camp in Austria.
The four Chelsea players, plus Portsmouth's David James, who were involved in the FA Cup final, arrive tomorrow, meaning injured midfielder Gareth Barry will be the only absentee.
Happily for Capello, everyone has been able to play some part in the opening two days of training.
Quite how far that extends in Ledley King's case is a moot point.
King is not able to train properly due to his chronic knee problems, although that did not prevent Capello picking him in his 30-man provisional squad.
However, the Italian will need to be certain the Tottenham captain can make a meaningful contribution in South Africa before handing him his ticket.
King's ability is certainly not in question. However, getting up to speed with the defensive formations of a coach he has never previously worked with, or players he has rarely played alongside is not going to be easy.
The same goes for Jamie Carragher, who has abandoned his international retirement for one last shot at the biggest prize the game has to offer.
But for someone who cannot train, the task is almost impossible, so Capello will need to assess just how much work King can do over the next fortnight before pursuing the matter any further.
Although the snow-capped mountains make a stunning visual backdrop to the work England are doing, the next fortnight requires focus from the Three Lions party if they are to get themselves in the best possible shape to mount a realistic World Cup bid.
And, although Walcott accepts there will be tough challenges ahead, starting with the Group C opener against the United States in Rustenburg on June 12, he is convinced England are capable of overcoming them.
"We have to believe we can win the tournament," he said.
"Obviously Spain are one of the big favourites. They won the European Championships and that was a great achievement.
"But we have nothing to fear because we've got some fantastic players.
"If you look at us individually there are some great players and if you look at the way we qualified, it shows that those individuals are playing together as a team.
"We just want to go one step further at the World Cup and bring it back for the fans."
Meanwhile, England are guaranteed to play in front of a sell-out Wembley on May 24, when they tackle Mexico.
The FA have posted house-full signs for the last game on home turf before Capello and his players head to South Africa, although preparations will not be concluded until the Three Lions tackle Japan in Graz on May 30.