His squad includes a couple of players considered unfortunate to miss out on selection for Steve McNamara’s main squad, including stand-by player Brett Ferres, who travelled with the main squad to their South Africa training camp.
Purtill said: “We’ve had a great period of preparation and the boys are really fired up for this game.
“It’s been quite a challenge for us this year: we have had our biggest turnaround in terms of new faces and the squad has come together really quickly.
“The players have worked really hard and the level of commitment has never been higher: I’m sure they will do a great job on Saturday.
“Rugby League is a tough game and injuries are a fact of life. The Knights players are the back-up for England’s World Cup squad and the game is a chance for them to show they are ready to step in should they be needed.”
1 Tommy Makinson (St Helens, Wigan St Judes)
2 Iain Thornley (Wigan Warriors, Wigan St Patricks)
3 Josh Jones (St Helens, Blackbrook)
4 Zak Hardaker (Leeds Rhinos, Featherstone Lions)
5 Ben Cockayne (Wakefield Trinity Wildcats, Normanton Knights)
6 Daniel Sarginson (London Broncos, Hemel Stags)
7 Sam Powell (Wigan Warriors, Wigan St Patricks)
8 Tom Burgess (South Sydney Rabbitohs, Dewsbury Moor)
9 Josh Hodgson (Hull KR, East Hull)
10 Scott Taylor (Wigan Warriors, Skirlaugh)
11 Brett Ferres (Huddersfield Giants, Smawthorne Panthers)
12 Elliott Whitehead (Catalan Dragons, West Bowling)
13 Dominic Crosby (Wigan Warriors, Wigan & Leigh College)
14 Chris Green (Hull FC, Skirlaugh)
15 Jack Hughes (Wigan Warriors, Wigan St Judes)
16 Michael Lawrence (Huddersfield Giants, Newsome Panthers)
17 Kieran Dixon (London Broncos, Hemel Stags)
18 Brad Singleton (Leeds Rhinos, Barrow Island)
19 Josh Bowden (Hull FC, Hull Wyke)
20 Logan Tomkins (Wigan Warriors, Wigan St Patricks)