Capello's squad will go through their paces for the first time on Tuesday morning ahead of Saturday's friendly with Slovakia.
But no one is expecting King to be there as the Tottenham defender has already admitted his right knee is so fragile he cannot risk it during the week if he is to get through a game on a weekend.
Under such circumstances, it is a major shock Capello has picked the 28-year-old, who last played for his country in 2007.
But the Italian has been impressed enough by King's recent performances at club level to deem the player worthy of further analysis, although Spurs will be kept informed every step of the way.
"The England management have spoken to Tottenham Hotspur FC today and explained that they will take no risks at all with Ledley King," said an FA spokesman.
"They fully understand the player's injury situation but they wanted to have a close look at him in the team environment as Ledley has not previously been part of a Fabio Capello squad.
"He will be monitored during the week by the England and Tottenham Hotspur medical staff before any decision on training or playing is made."
With no further medical update coming out of the England camp following their arrival in Watford on Monday night, Capello should have a decent turn-out at Arsenal's London Colney training complex.
Everton's Leighton Baines will get his first experience of training with the seniors, while Ben Foster and Aaron Lennon return after lengthy absences.
Capello has already pledged to use his maximum six substitutes against Slovakia, the warm-up for a crucial World Cup qualifier with Ukraine on April 1 when the England coach is convinced the Three Lions supporters will dismiss any lingering reservations and get fully behind their team.
"When you play with a very important team like England you have to live with pressure," said Capello.
"The Ukraine game is very important to us. Their league only started at the beginning of March so their players will be very fresh.
"Ours are a little bit tired. But I think the fans will help us this time. We will have 12 players on the pitch."