London - Leicester centre Manu Tuilagi was recalled to the England fold on Thursday after being named in a 37-man squad for a three-day training camp.
Tuilagi has not played for England since 2016 due to a succession of serious injuries.
Seven of England's British and Irish Lions contingent will each spend a day at the camp in southwest London, but not train, with the eight other Lions skipping the camp entirely.
"We are at an incredibly important stage with two years to go to the Rugby World Cup in Japan and there is still a big step to make if we want to be the number one team in the world," said England head coach Eddie Jones in a press release.
"We are going to have to be meticulous in preparation in everything we do as we build towards Tokyo and that is why this camp is vital ahead of this season.
"The players, coaches and staff will use these three days to reconnect and ensure we are all clear on what our priorities and expectations are ahead of the Premiership season, as well as the upcoming Old Mutual Wealth Series (in November)."
The seven Lions who will report to the camp for medical check-ups and various reviews are Dan Cole, Owen Farrell, Jamie George, Maro Itoje, Jack Nowell, Kyle Sinckler and Anthony Watson.
Harlequins' 18-year-old fly-half Marcus Smith has been included in the squad after taking part in some England training sessions at the end of last season.
Saracens number eight Billy Vunipola, who missed the Lions' tour of New Zealand through injury, and Leicester scrum-half Ben Youngs, a Lions absentee for family reasons, also made the cut.
England will have further training camps in Oxford and Portugal before Jones names his squad in late October for the November Tests against Argentina, Australia and Samoa.
England training squad
Backs: Mike Brown (Harlequins), Danny Care (Harlequins), Nathan Earle (Saracens), Owen Farrell (Saracens), George Ford (Leicester), Piers Francis (Northampton), Alex Lozowski (Saracens), Harry Mallinder (Northampton), Joe Marchant (Harlequins), Jack Maunder (Exeter), Jonny May (Gloucester), Jack Nowell (Exeter), Richard Wigglesworth (Saracens), Henry Slade (Exeter), Marcus Smith (Harlequins), Denny Solomona (Sale Sharks), Manu Tuilagi (Leicester), Anthony Watson (Bath), Ben Youngs (Leicester)
Forwards: Dan Cole (Leicester), Luke Cowan-Dickie (Exeter), Tom Curry (Sale Sharks), Tom Dunn (Bath), Charlie Ewels (Bath), Ellis Genge (Leicester), Jamie George (Saracens), Dylan Hartley (Northampton), Nathan Hughes (Wasps), Nick Isiekwe (Saracens), Maro Itoje (Saracens), Joe Launchbury (Wasps), Chris Robshaw (Harlequins), Kyle Sinckler (Harlequins), Sam Underhill (Bath), Harry Williams (Exeter), Mark Wilson (Newcastle), Billy Vunipola (Saracens)