The inclusion of the Sussex wicketkeeper/batsman is a direct consequence of the new regulations, introduced by the International Cricket Council, which allow teams to field a substitute.
England and Australia will be the first teams to play under the new rules, at Headingley on Thursday. Many expected the position to be filled by an all-rounder, but England's selectors have opted for a hard-hitting specialist batsman. Prior's selection suggests that England will be looking to bat second in each of the three games, a move which would allow them to add an extra batsman to their team in the pursuit of Australia's total.
It is a risky decision but it makes sense because a batsman can bat for up to 50 overs in a one-day game, whereas a bowler can only bowl 10 overs.
David Graveney, England's chairman of selectors, was keen to stress that Prior's selection would not pose any threat to Geraint Jones' place in the team.
"Matt has been chosen purely as a specialist batsman, although he will obviously provide cover for Geraint Jones in the event of injury," Graveney said.
"Matt has been chosen as an impact player who is in good form, and his inclusion will give Duncan Fletcher and Michael Vaughan more options for their choice as substitute."
Prior made his one-day debut during England's controversial tour of Zimbabwe. The 23-year-old scored 35 in his only game but his attitude impressed the England management. The South African-born right-hander spent the remainder of the winter at the National Academy, and on the England A tour of Asia, where he again caught the eye.
His one-day form this season has been outstanding. In domestic one-day cricket he has scored 616 runs at an average of 56. But it is his strike-rate - runs per 100 balls - of more than 100 that has led to his selection. Prior is likely to receive a few verbals from the Australians, after an incident in the match between Sussex and Hampshire earlier this year. During the game Prior became involved in a sledging row with Australia's Shane Warne and Simon Katich, and came off second best.
"I'm delighted to get another opportunity with England," Prior said. "I felt it went well during the winter. I had a little taste of international cricket and feel I know what to expect, although obviously it's going to be different against a team like Australia."
ENGLAND SQUAD: M Vaughan (c), P Collingwood, A Flintoff, A Giles, D Gough, S Harmison, G Jones, S Jones, J Lewis, K Pietersen, M Prior, V Solanki, A Strauss, C Tremlett, M Trescothick.Reuse content