Christopher Bell is on the phone and there is something odd in his tone. I've been hoping to hear from him, having planted messages all over the place, trying to organise an interview with him about his new job as director of the Edinburgh Festival Chorus, probably the top choral job in the UK.

"You want an interview, but I was going to call you anyway," said the usually ebullient Irishman, sounding strangely subdued and tense. "I have a brain tumour. It has to be operated on immediately.

"You've been there and I'd like to talk to you about it. I'll do your interview as well, but it will have to be very soon."

All plans were ditched and, within 18 hours, we met up at the City Hall, 90 minutes before he was due to conduct a concert with his National Youth Choir of Scotland (NYCoS), a concert he fully intended to see through.

Christopher Bell, for those who might not be aware, is probably the best known and most-loved musician working in Scotland today.

For many years he was director of the RSNO Chorus and Junior Chorus. He's still in change of the Juniors.

If you've ever been to an RSNO Christmas concert, 47-year-old Bell is the madcap entertainer with the genius for communicating with and galvanising an audience.

Until recently, he was also artistic director of the hugely popular and successful Children's Classic Concerts series, to which thousands of families flock on a regular basis.

He is a man for the singing, through and through, and today presides over an extraordinary living choral tradition in Scotland, NYCoS, which he founded 12 years ago. Scotland sings, thanks to this man.

And now we sit quietly in the City Hall, swapping tumour stories. He was working in America, where he is chorus director at the Grant Park Festival in Chicago, just a few weeks ago, when he noticed something. He was experiencing a kind of seizure (his description) in his fingers. He had, variously, a numbness and tingling sensation in the area.

He decided to take off his jacket. He couldn't get it off. "I told myself: Christopher; take off your jacket" and his arm shot out at 90 degrees to his body, in the wrong direction.

"It lasted about four minutes. I thought it was a trapped nerve and didn't say anything to anybody."

About a week later, it happened again. "I thought I'd had a stroke and was dying." A colleague working with him at the Chicago festival phoned her mother, who works in A&E in Michigan, described his symptoms, and passed on the blunt message: "Your arm does not move on its own. Something is telling your arm to move and we need to find out what it is."

Bell was fast-tracked into hospital in Chicago, given an MRI scan, brain-mapped, and all the rest of it, and within 10 hours was given the diagnosis that there was "an unwanted growth" pressing on his brain, and it had to come out asap. .

He pulled out of his festival commitments, brought in heavyweight replacements and headed home.

He was fast-tracked again at the Western General in Edinburgh, given the same diagnosis he'd received in the States (a meningioma pressing on the brain), told on the Friday he had to check in on the Monday and be operated on the following morning. Bell being the man he is, decided to do his concert on the Saturday, do the interview with me immediately before that, then get ready for his op. How did he cope with the news?

"Telling people was difficult. As soon as you use the T-word, people immediately assume you're a goner. I want to leap about in front of the chorus, cracking dirty jokes and shouting: It's still me; I haven't changed; I'm still here." At that point, an hour before his concert with NYCoS, he still hadn't decided whether to tell them.

He reflected deeply on his new appointment with the Edinburgh Festival Chorus, and his first festival with them, starting on August 8.

"I have looked at this job for 20 years. I've wanted this job so much. I can make a difference here. I can really make a difference. People will already notice a difference this year."

He leaned forward in his chair. "I am going to be fine. Fine. I'm not going to let this bloody thing stop me."

Christopher Bell entered the Western General Infirmary in Edinburgh last Monday (14th) and was operated on the following day. On Thursday he was sent home. He e-mailed me to say they had "got it out" and it had gone off for analysis.

He was fine, though "knackered", and awaited the arrival of his mum to administer "lots of TLC and cups of tea".