King has a debilitating problem in his right knee that prevents him from doing any sessions with his Spurs team-mates during the week.
The only contact he has with them is on the day before a game when King watches training to learn the moves he will be part of 24 hours later.
It is a testimony to King's remarkable ability that he has performed so well this season. And even more incredible to think Capello might select him.
Yet that possibility is the inevitable conclusion after King was named in a 24-man squad by the England coach for next Saturday's friendly with Slovakia at Wembley and the far more important World Cup qualifier against a dangerous Ukraine outfit at Wembley on April 1.
King turned in a superb performance at White Hart Lane on Saturday during Tottenham's win over Chelsea and it seems the Italian is willing to overlook King's training ground absences.
The 28-year-old's problem stems from a series of cartilage operations which effectively mean bone rubs against bone during physical exertion.
King has such swelling afterwards, it takes days to subside properly, so when the England squad meet up tomorrow evening at their Watford HQ, that is the condition Capello is likely to find in a player who last appeared for his country before the 2006 World Cup.
At least King will have some company as the two-year international exile of Spurs team-mate Aaron Lennon has also been brought to an end while, as predicted, Manchester United keeper Ben Foster is included by Capello for the first time.
The one new face is Everton's Leighton Baines.
He may only be profiting from the hamstring injury that has ruled out Wayne Bridge but Baines' name has been cropping up in conversations about England lately, just as it did when he was part of Wigan's charge to the Premier League.
His excellent goal at Portsmouth yesterday cannot have done Baines any harm either, even if he must rely on Capello not wanting Ashley Cole to play the full game on Saturday before attempting to subdue Ukraine.
If the performances of King and Baines have caught the eye, Capello clearly feels the form of both Ashley Young and Gabriel Agbonlahor has dipped as Aston Villa have slid out of the battle for a Champions League slot.
Both men were involved in the defeat to Euro 2008 winners Spain last month but now find themselves excluded, along with James Milner and Luke Young.
The defeat in Seville has been interpreted by many as proof England remain someway off being a world power.
However, Capello takes the alternative view, claiming the performance proved his team can take on the best.
And, the returns of Wayne Rooney and Steven Gerrard, who have had such contrasting fortunes over the weekend, plus Rio Ferdinand, who pulled out a month ago with a stomach bug, do at least suggest the Three Lions are a far stronger unit than they were a couple of years ago.
England squad for matches against Slovakia and Ukraine:
Foster (Man Utd), Green (West Ham), James (Portsmouth); Baines (Everton), A Cole (Chelsea) Ferdinand (Man Utd), Jagielka (Everton), Johnson (Portsmouth), King (Tottenham), Lescott (Everton), Terry (Chelsea), Upson (West Ham); Barry (Aston Villa), Beckham, Carrick (Man Utd), Downing (Middlesbrough), Gerrard (Liverpool), Lampard (Chelsea), Lennon (Tottenham), Wright-Phillips (Man City); C Cole (West Ham), Crouch (Portsmouth), Heskey (Aston Villa), Rooney (Man Utd).