At 5.45pm on Friday, when Graeme Swann walks out to toss up with his West Indian counterpart, Darren Sammy, the end of one of the more improbable journeys in English cricket will have been reached.

In the winter of 1999-2000, Swann was a brash young upstart on England's tour of South Africa under Nasser Hussain, and so offended his elders and betters that he was banished from the set-up for the next seven years. Now, 12 years on, he is England captain, and regardless of the circumstances in which the honour has come about, he is ready to embrace the sort of responsibility that no-one ever imagined he was capable of producing.

"My mother's prophecy comes true at last," Swann told reporters at The Oval. "She always said I would captain England but I am not sure which sport she was thinking of. It's great. I am delighted. It is a tired old cliché but when you do get asked it is a proud moment and I have surprised myself about how excited I have been about it."

As the fifth England captain of a memorable summer, Swann knows his role is very much a temporary measure that only came about because of injuries to the Twenty20 captain and vice-captain, Stuart Broad and Eoin Morgan. Nevertheless, at the age of 32, Swann is the gnarled old veteran in a youthful squad that includes a host of players who are barely out of their teens, and as such, he recognises the need to lead by an example that perhaps doesn't come entirely naturally to him.

Swann first played for England when he was the same age as the likes of Joss Buttler and Alex Hales, and by his own admission, he was far from ready for the big time. However, he believed that series such as the one about to take place could have helped him develop his game.

"Graeme Swann the captain would never pick Graeme Swann the kid," he said. "The one regret I have about being 19 or 20 is that there was not Twenty20 around in those days. I'm sure I would be pretty good at it because I could bat in those days. I would have had a way of staying in the England squad for a few years while I developed my skills in the longer form. That is the only regret I have got about the young, lunatic Graeme Swann. He is still in there but I manage to hide him most of the time."

Now, however, it is time to put on his more serious face. "For all the impression I give about messing around all the time, it is not always like that," Swann said. "Most of the joshing around is in the Anderson-Bresnan corner, but I have curbed that this week because I can't be seen to be taking the mickey out of my players. Some of these guys are coming in for the first time, so they are wide eyed and excited about playing. Going in with a group of gnarled old pros, half of whom don't like you and the other half like you even less, it is nice to have a young and exciting squad to be in charge of."

Swann's previous captaincy experience is limited in the extreme. At Nottinghamshire, what few opportunities might have existed were limited by the presence of the New Zealand skipper, Stephen Fleming, whom he rated as arguably the best captain in the world, while Fleming's successor Chris Read cemented his credentials last summer with a memorable victory in the County Championship.

"I have always harboured ambitions of captaining at first-class level and it is nice that I have got a chance, if only for a couple of games, to show the inner workings of my mind, that I think are brilliant," said Swann. "Normally it is a case of if you hang around long enough you might get a chance, so I am delighted. I feel like a senior player in this group now and when I looked at this squad for the matches, I thought it would be exciting to be in charge of that lot."

Aside from providing four tidy overs, Swann admitted that there was only so much he could do to have a direct influence on the tactics in Twenty20 cricket. "It is a reactions game," he said. "You can start with grandiose plans about how you want to start, and they can change quickly. I like to think I will be attacking, but I am not sure it will be too maverick or out of the box. It is important in this form of the game to take wickets. That is what won us the World Twenty20 [last year]. At any given stage during the game, we will be thinking where is the best chance to take wickets."

With West Indies also set to field a young and inexperienced side, the true value of these two fixtures has been called into question. However, Swann was adamant that, in 12 months' time in Sri Lanka, the team that takes the field to defend the World Twenty20 is likely to contain a sizeable number of the rookies on show this weekend - among them Jonny Bairstow, whose dynamic debut in the final ODI against India was proof of his hard-hitting abilities.

"These are guys who have been brought up on a diet of Twenty20 and they are close [to the first eleven]," said Swann. "I can't see that team next year being vastly different from this squad. Obviously the odd player will come back in but cricket is a game in which new superstars emerge all the time and this team has got the potential for four or five megastars in it.

"The way the likes of Bairstow played the other night was a glimpse into the potential he has got," Swann added. "We have not seen anything of Stokes but we know what potential he has got, and then there are people like Joss Buttler who does it day in, day out for Somerset and he will come to the party sooner rather than later. We have got the potential for the most exciting top six in world cricket which is great."

With that in mind, the chance to play two extra Twenty20s in the build-up to Sri Lanka was not to be sniffed at, given how few fixtures are allocated in any given tour. "It defies belief that we only have one Twenty20 match [per series]," said Swann. "It is the biggest game in the short format and somewhere down the line we will have to treat it a bit more seriously and play series of Twenty20 games. We are World Champions but going into Sri Lanka we will only play four or five games in this format before that World Cup starts."

Andrew Miller is UK editor of ESPNcricinfo