Armitage is the brother of Test full-back Delon
London Irish flanker Steffon Armitage has replaced Lewis Moody in England's elite squad ahead of the Six Nations.
Moody is out for up to three months after breaking his ankle during training with his club Leicester.
Armitage, 23, who moves up from the Saxons squad, is the brother of Delon, who played at full-back in the autumn.
England have also summoned two members of the 2003 World Cup-winning squad, lock Ben Kay and flanker Joe Worsley, plus Bath wing Matt Banahan, as cover.
All three were in the Saxons squad, but will cover the absences of Tom Palmer, who will miss the entire Six Nations, Tom Rees - out for the first three matches - and Ugo Monye, who will remain in England for treatment on a back problem.
Bath back-row Michael Lipman has also been summoned as cover to the elite squad's training camp in Portugal this week.
Steffon has been in very good form for London Irish this season
Lipman, not currently a member of the elite squad, was knocked out cold in the first quarter of Bath's 3-3 draw with Toulouse on Sunday, but after lengthy treatment was able to walk off the field himself.
He will be assessed by the England medical staff on his arrival in Portugal on Monday.
But Armitage, in the absence of Rees and Moody, is now a strong contender to start England's opening Six Nations match against Italy on 7 February.
"Steffon has been in very good form for London Irish this season and deserves his opportunity," said England team manager Martin Johnson.
Prop Matt Stevens has already been removed from the elite squad after failing a drugs test, with his place taken by Julian white.
The elite squad trained for the first time on Monday at their camp in Portugal, with the exception of the players involved in Sunday's Heineken Cup and European Challenge Cup matches.
After the elevation of Armitage to the senior squad, Harlequins captain Will Skinner has been added to the second-string Saxons squad.
But Skinner will remain with Quins this week for their Guinness Premiership match against Northampton on Saturday.
Revised England elite player squad (32):
Forwards: Tim Payne (Wasps), Andrew Sheridan (Sale), Phil Vickery (Wasps), Julian White (Leicester), George Chuter (Leicester), Dylan Hartley (Northampton), Lee Mears (Bath), Steve Borthwick (Saracens), Nick Kennedy (London Irish), Tom Palmer (Wasps), Simon Shaw (Wasps), Steffon Armitage (London Irish), Tom Croft (Leicester), James Haskell (Wasps), Tom Rees (Wasps), Nick Easter (Harlequins), Luke Narraway (Gloucester).
* Also training with the senior squad: Ben Kay (Leicester), Michael Lipman (Bath), Joe Worsley (Wasps).
Backs: Delon Armitage (London Irish), Olly Morgan (Gloucester), Mathew Tait (Sale), Mark Cueto (Sale), Paul Sackey (Wasps), Ugo Monye (Harlequins), Jamie Noon (Newcastle), Mike Tindall (Gloucester), Riki Flutey (Wasps), Shane Geraghty (London Irish), Danny Cipriani (Wasps), Toby Flood (Leicester), Danny Care (Harlequins), Harry Ellis (Leicester), Ben Foden (Northampton).
* Also training with senior squad: Matt Banahan (Bath).