Club captain Ed Slater has been included alongside Leicester Tigers colleagues Dan Cole, Geoff Parling, Ben Youngs and Tom Youngs in England's extended training squad for the Rugby World Cup.Head coach Stuart Lancaster has named a 50-man group to meet up at Pennyhill Park on June 22 to begin preparations for the tournament which starts with a match against Fiji at Twickenham Stadium on September 18.   The uncapped Slater returned from a knee injury to make his first Tigers appearance of the season in Round 21 of the Aviva Premiership campaign this month, joins his four club colleagues in the squad. Tom Croft is omitted at this stage as he continues his comeback from a shoulder injury.   Lancaster said: “We are excited to name this extended squad which allows us to look at a wide group of players who have been pushing hard for selection in training with us or playing well for their clubs this season.   “It’s great to be able to include Alex Corbisiero, Joe Launchbury, Ben Morgan, Ed Slater and David Wilson who missed the Six Nations because of injury and are close to returning to play or have recently begun playing again.   “Ben Foden, Joe Simpson and Tom Croft have not been included at this stage due to ongoing rehabilitation from injury but will hopefully come into consideration nearer the tournament.”   England face the Barbarians at Twickenham on May 31, with that squad to be announced this Sunday once the Aviva  Premiership finalists are known as players from the losing semi-finalists could be involved.   There are also fixtures against France home and away, and Ireland at Twickenham, as part of the QBE Internationals in the build-up to RWC 2015.   The training squad will be reduced ahead of a training camp in Denver and cut again before the QBE Internationals, with the final 31 players for the Rugby World Cup being announced by the end of August.   England Rugby World Cup training squad  Chris Ashton (Saracens) Dave Attwood (Bath Rugby) Brad Barritt (Saracens)  Kieran Brookes (Newcastle Falcons) Mike Brown (Harlequins)  Luther Burrell (Northampton Saints)  Sam Burgess (Bath Rugby) Danny Care (Harlequins)  Danny Cipriani (Sale Sharks) Calum Clark (Northampton Saints) Dan Cole (Leicester Tigers) Alex Corbisiero (Northampton Saints) Luke Cowan-Dickie (Exeter Chiefs) Elliot Daly (Wasps) Lee Dickson (Northampton Saints) Kyle Eastmond (Bath Rugby)  Nick Easter (Harlequins) Owen Farrell (Saracens)  George Ford (Bath Rugby)  Alex Goode (Saracens)  Dylan Hartley (Northampton Saints)  James Haskell (Wasps) Maro Itoje (Saracens) Jonathan Joseph (Bath Rugby) Courtney Lawes (Northampton Saints) Joe Launchbury (Wasps) George Kruis (Saracens)  Matt Kvesic (Gloucester Rugby) Joe Marler (Harlequins)  Jonny May (Gloucester Rugby)  Stephen Myler (Northampton Saints) Ben Morgan (Gloucester Rugby) Matt Mullan (Wasps) Jack Nowell (Exeter Chiefs)  Geoff Parling (Leicester Tigers) Chris Robshaw (Harlequins)  Henry Slade (Exeter Chiefs) Ed Slater (Leicester Tigers) David Strettle (Saracens) Billy Twelvetrees (Gloucester Rugby) Mako Vunipola (Saracens)  Billy Vunipola (Saracens) Anthony Watson (Bath Rugby) Rob Webber (Bath Rugby)  Richard Wigglesworth (Saracens) David Wilson (Bath Rugby) Tom Wood (Northampton Saints) Marland Yarde (Harlequins) Ben Youngs (Leicester Tigers)  Tom Youngs (Leicester Tigers)