And Jefferies insisted the midfielder, who looked set to leave Hearts in the summer, could still have years ahead of him at Tynecastle.
Ghana's former FA chief Dr Nyaho Tamakloe yesterday claimed that Kingston and a number of his other international team-mates had lied about how old they were.
Nyaho says he believes the players, who included Chelsea's Michael Essien, Sunderland's John Mensah and John Pantsil of Fulham, have become 'burnt out' and prone to injury because they are older than they have admitted. Kingston has struggled with a back strain over the last fortnight and has also been posted missing for much of this season due to hamstring problems.
However, having worked with Kingston over the last few months since his appointment as Hearts manager, Jefferies insisted the 29-year-old can still be a pivotal player for the Jambos.
Making light of Tamakloe's claims he said: "When I heard, right away I applied for a bus pass for him!
"I had heard a lot of stories about a lot of things in here but until you come in and see it for yourself, you don't know. Coming in when we did gave us the chance to see players rather than walk in during pre-season and having to use that to try and suss things out."
Jefferies revealed that Kingston has expressed a desire to continue his career with Hearts and believes that supporters could soon see the best of the Ghanaian again. However he warned that he will be keeping a close eye on the player to ensure he sticks to his word: "He's been fine. I had a chat with him about the problem he had and I asked him if he still had the desire to play for the club.
"He said yes so all I could do was take him at his word, but I told him I would be watching to make sure it wasn't just all words. And he has done terrific. He's been great in training. When he has gone out and played he has done his best, he has tried hard, he has proved things to people. And now you see comments saying we are getting the best out of him."