England will retain 26 players for training - including four from Leicester Tigers - ahead of Sunday's RBS 6 Nations match against Ireland.The squad will train on Wednesday before re-assembling at Pennyhill Park on Thursday evening and flying to Dublin on Friday.   Head coach Stuart Lancaster said: “Preparation has gone well and we’ve had a good build-up so far. The guys who played against Wales and Italy did really well and the good thing is that others who are now fit and training are pushing hard for selection.     “We’ve had to make some tough decisions but it’s a good position to be in and those players going back to their clubs have another big weekend ahead to lay down a marker for later in the tournament.”   Kieran Brookes pulled up in training with a hip flexor strain so Henry Thomas has been called in for training. Mike Brown completed a running session yesterday and should be able to take part in non-contact training with the squad.   Forwards Dave Attwood (Bath Rugby) Kieran Brookes (Newcastle Falcons) Dan Cole (Leicester Tigers) Tom Croft (Leicester Tigers) Nick Easter (Harlequins) Dylan Hartley (Northampton Saints) James Haskell (Wasps) George Kruis (Saracens) Joe Marler (Harlequins) Chris Robshaw (Harlequins)(c) Henry Thomas (Bath Rugby) Billy Vunipola (Saracens) Mako Vunipola (Saracens)  Tom Youngs (Leicester Tigers) Backs Mike Brown (Harlequins) Luther Burrell (Northampton Saints) Danny Cipriani (Sale Sharks) George Ford (Bath Rugby) Alex Goode (Saracens) Jonathan Joseph (Bath Rugby) Jack Nowell (Exeter Chiefs) Chris Pennell (Worcester Warriors) Billy Twelvetrees (Gloucester Rugby) Anthony Watson (Bath Rugby) Richard Wigglesworth (Saracens) Ben Youngs (Leicester Tigers)   Retained in camp for recovery Manusamoa Tuilagi (Leicester Tigers)   Players released to Aviva Premiership clubs Brad Barritt (Saracens) Danny Care (Harlequins) Calum Clark (Northampton Saints) Alex Corbisiero (Northampton Saints)   Kyle Eastmond (Bath Rugby) Courtney Lawes (Northampton Saints) Jonny May (Gloucester Rugby) Geoff Parling (Leicester Tigers) Rob Webber (Bath Rugby) Tom Wood  (Northampton Saints)