"It's a lifetime dream for me to represent my country, especially in a World Cup," Purdham told Radio 5 Live.
Wingers Mark Calderwood and Lee Smith, plus Bradford duo Jamie Langley and Paul Sykes are included, but Smith's decision to take just four specialist props - captain Jamie Peacock, Adrian Morley, James Graham and Maurie Fa'asavalu - but not Fielden has caused some ripples.
"If you take five front rowers, that's over a fifth of your squad so that would be a gamble too," he said.
"There's got to be a certain amount of versatility and there are some players who play in the back row that I wouldn't hesitate in pushing forward to the front row. There's a gamble whichever way you go."
Fielden could be on Smith's stand-by list for the tournament where England are in a group of four teams, along with hosts and holders Australia, New Zealand and Papua New Guinea.
The top three sides make it through to the semi-finals.
England will warm up for the World Cup with a game against Wales at Doncaster's Keepmoat Stadium on Friday.
England: Keith Senior, Danny McGuire, Rob Burrow, Jamie Peacock (captain), Gareth Ellis, Kevin Sinfield, Jamie Jones-Buchanan, Lee Smith (all Leeds), Paul Wellens, Ade Gardner, Leon Pryce, James Graham, James Roby, Maurie Fa'asavalu, Jon Wilkin (all St Helens), Rob Purdham (Harlequins), Mark Calderwood, Mickey Higham, Gareth Hock (all Wigan), Martin Gleeson, Adrian Morley, Ben Westwood (all Warrington), Jamie Langley, Paul Sykes (both Bradford).



