Winger Elliott is one of 11 previously capped players in the 32-man group and along with Nutley signed a first team contract with the Saints as recently as last month.
Day meanwhile, who is capped by England at Under-18 level, has been a regular for both the Wanderers and the Saints Academy - both teams who have performed well thus far in 2011/12.
The announcement comes just 24 hours after eight Saints were called up by the senior England EPS, making up a quarter of the overall squad.
ENGLAND U20 ELITE PLAYER SQUAD
FORWARDS: Luke Cowan-Dickie (Exeter Chiefs), Nick Auterac (Saracens), Alec Hepburn (London Wasps), Kyle Sinckler (Harlequins), Nathan Morris (London Wasps), Scott Spurling (Saracens), Koree Britton (Gloucester Rugby), Sam Twomey (Harlequins), George Merrick (Harlequins), Tom Price (Leicester Tigers), Dom Barrow (Leeds Carnegie), BEN NUTLEY (Northampton Saints), Chris Walker (Leeds Carnegie), Matt Kvesic (Worcester Warriors), Billy Vunipola (London Wasps), Will Skuse (Bath Rugby), Jack Clifford (Harlequins)
Dan Robson (Gloucester Rugby), ALEX DAY (Northampton Saints), Ben Spencer (Saracens), Tom Heathcote (Bath Rugby), George Ford (Leicester Tigers), Ryan Mills (Gloucester Rugby), Sam Hill (Exeter Chiefs), Elliot Daly (London Wasps), JAMIE ELLIOTT (Northampton Saints), Mark Jennings (Sale Sharks), Marland Yarde (London Irish), Charlie Walker (Harlequins), Will Addison (Sale Sharks), Ben Ransom (Saracens), Jack Nowell (Exeter Chiefs)