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For 364 of the other dates in the year, the number 31 is usually associated with the number of days in certain months, a card game or the international dialling code for the Netherlands. But on Thursday, the focus will be on that number as Stuart Lancaster confirms the players he has picked to form England's Rugby World Cup squad.

Here we look at the last minute headaches for Lancaster and pick out those already inked into the squad.

Props

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Lancaster is expected to take five props to the World Cup with Joe Marler, Mako Vunipola, Dan Cole and Davey Wilson fairly assured of their places in the final mix. The last spot is between Kieran Brookes and Alex Corbisiero. Given the latter's lack of game time, Brookes is likely to complete the quintet.

Hookers

Jamie George was singled out for praise by Lancaster following Saturday's defeat in Paris and he should be named alongside Rob Webber and Tom Youngs in the final 31. Luke Cowan-Dickie could sneak in as the third hooker but the other three look to be ahead of him in the pecking order. Dylan Hartley's World Cup hopes hinge on one of the other No.2s picking up an injury. The set piece is a concern for England at present and they will need their hookers to re-find their accuracy at the lineout ahead of their opener against Fiji on Sep. 18.

Locks

Nick Easter is still largely seen as a back-rower despite his ability to play in the second-row so the smart money is on England taking four specialist locks. Dave Attwood is likely to be the unlucky man to miss out with George Kruis, Geoff Parling, Joe Launchbury and Courtney Lawes all going.

Back-row

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Chris Robshaw, Billy Vunipola, Tom Wood and James Haskell are all set to make the cut so it will come down to Ben Morgan versus Nick Easter for the final spot. Calum Clark could yet gate-crash the final party but Easter's impact against France in Paris will have seen him move up in the pecking order and his experience over Clark's may give him the edge. Morgan was England's standout player last November but he suffered a leg break in January and has only played 40 minutes of Test rugby since then. His lack of match time may prove to be critical.

Scrum-half

Three scrum-halves remain and all three are likely to be in the 31. While Australia have the luxury of Matt Giteau, who can cover No.9, England lack a hybrid in that mould. Richard Wigglesworth, Danny Care and Ben Youngs are all set to be in the squad but after a low-key performance against France on Saturday, Youngs faces a battle to hold on to the first-choice spot.

Fly-half

Danny Cipriani will be left out of the 31 leaving George Ford and Owen Farrell as the two specialist fly-halves. Ford struggled against France last weekend so Farrell may yet go into the World Cup as England's first choice 10.

Centres

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This is perhaps the biggest area of ambiguity ahead of the squad announcement. The centres have been the problem area in the Lancaster reign with a number of different contenders having been given a chance but few making the spot their own. Henry Slade could yet make the squad and it seems to be between him, Luther Burrell and Sam Burgess for two of the four spots on offer with Billy Twelvetrees missing out. Brad Barritt and Jonathan Joseph can feel assured of their spots in the squad. Burgess only has 70 minutes of Test rugby to his name but England are admirers of his attitude and physicality while Burrell was seen to be almost a shoe-in for a spot in the team but Slade's impressive debut puts his spot under pressure. It's the old adage of the piano-player being up against the piano-shifter.

Back three

With Cipriani missing out, fullbacks Alex Goode and Mike Brown are sitting pretty to make the final 31 while the three remaining wingers - Jonny May, Anthony Watson and Jack Nowell - are all likely to make the cut. The trio only have 34 England caps between them so they will have to show youthful exuberance is an able substitute for international experience.

Tom Hamilton predicts England's Rugby World Cup squad:

Forwards: D. Cole, J. Marler, M. Vunipola, D. Wilson, K. Brookes, J. George, R. Webber, T. Youngs, G. Kruis, J. Launchbury, C. Lawes, G. Parling, N. Easter, J. Haskell, C. Robshaw, B. Vunipola, T. Wood.

Backs: D. Care, R. Wigglesworth, B. Youngs, O. Farrell, G. Ford, B. Barritt, S. Burgess, J. Joseph, H. Slade, M. Brown, A. Goode, J. May, J. Nowell, A. Watson.