McGuire hasn't played for his country since 2009, due to a severe slump in form that has seen him drop down the pecking order behind the likes of Richie Myler and Danny Brough.
However, he looked back to his old self in 2012, combining superbly with club and international captain Kevin Sinfield as the Rhinos picked up their sixth Super League title in seven years.
Peacock, who himself is in contention for a place in Steve McNamara's squad for the World Cup, has now backed McGuire to be called up, as he believes the 30-year-old could provide the key to England's chances.
"The number of times he has shown up in the big games with big plays is just countless," the veteran said. "If we needed a try or someone to get on the end of something, Maggsy would be there and that shows how good a player he is.
"There's a lot of different potential combinations but if England are to do well in the World Cup, Maggsy has to be in the squad."