While diver Tom Daley is already something of a celebrity, neither he nor his coach expected him to be world 10-metre platform champion at the age of 15.

To his visible disbelief the pint-sized teenager stunned Chinese favourite Qiu Bo and Australian Olympic gold medallist Matthew Mitcham by taking the title in Rome's Foro Italico on Tuesday.

"It just hasn't sunk in yet," Daley told reporters the day after his greatest achievement.

"I just wanted to come here and put in a performance that I would be proud of. Now I am world champion it has surpassed my wildest dreams."

Coach Andy Banks was equally amazed. "It wasn't really part of the plan but we'll take it thank you very much," he told Reuters in a telephone interview from Rome.

"Our goal this year was to consolidate his confidence post Olympic Games and to go out on to the senior circuit as a player rather than the new kid on the block.

"He's certainly done that over the course of this year. He thrives on the adrenaline of going into a punch-up and his rivals know he's going to be bubbling and bouncing. That's another reason why they're a bit scared of him."

Far from getting carried away by Daley's surprise win however, Banks reminds himself about the unpredictable nature of diving.

"If you had that event today it would probably be a completely different result. You wouldn't have put your house on him winning. I guess that makes it more interesting, though it can also make it frustrating."

Another reason for Banks's caution is Daley's swift rise.

Daley was attracting media interest at the age of 10, with success in competitions, and when he won the European championships in March last year he made headlines around the world in the run-up to the Beijing Olympics.

It sparked a media storm in diving-mad China and, although the youngster handled the pressure in the individual event by finishing a respectable seventh, he and synchronised partner Blake Aldridge had a very public falling out.

Aldridge blamed Daley for their disappointing last-placed performance and revealed they had a spat over a mobile phone call before their final dive.

"He had a pop at me before the last dive. I saw my mum in the audience and I asked her to give me a call and Tom went to me: 'Why are you on the phone? We're still in the competition and we've got another dive to do'," Aldridge said at the time.

The duo's time together came to an end in February prompting a search for a new partner, and Daley was lining up in the Italian capital with 17-year-old compatriot Max Brick on Friday and Saturday.

The British teenagers have already picked up a silver medal at the Fort Lauderdale Grand Prix in Florida in May.

"From a relationship point of view it's a lot better," said Banks. "They're more mates and it has the potential to grow.

"Max actually told me yesterday: "It's going to be great, I'll be standing next to a world champion'."

While Daley's win on Tuesday came as a surprise to Banks, the youngster's increasing maturity does not.

"He has what he calls his "lives'. "Media lives' is one of them, his "school life', "diving life', "family life' and whatever.

He can switch from one to the other.

"He can be playing silly buggers in the gym and being typically 15-year-oldish one minute, and then go straight up to a microphone and put on a professional media head."

Another well-publicised hurdle for Daley to overcome has been at school, where he received a hard time from other pupils because of his fame.

"Throughout Tom's career even the bad things have become good," said Banks.

"If you look at the school thing yes it was a pain in the neck when it was happening and yes he was pulled out of school and couldn't go for a while, which wasn't good for him, but he's now gone to Plymouth College, who have bent over backwards for him."

At Daley's new school on England's south coast, Banks said, the swimming coach ran one of the only programmes in the country with a boarding house for swimmers, and his wife was the team's physiotherapist.

"She can now put into curriculum time his rehabilitation when there are injuries or niggles, for example."

Next year Daley will face another hurdle with major exams, though his new school are looking to programme the teenager's terms around diving events to help him.

"Although it needed a bad thing to happen in the first place to kick start it, we're very happy," Banks said.