Simon Halsey's 25 years as director of the CBSO's choruses have seen a steady growth in their range and international renown.
It may seem hard to believe, but it's now a quarter of a century since the then 24 year-old Simon Halsey took over as director of the City of Birmingham Symphony Chorus.
He will be celebrating the milestone this Saturday by conducting the chorus and the CBSO in two works very dear to him, Holst's Savitri and Vaughan Williams' A Sea Symphony.
"It certainly doesn't feel like 25 years," he says emphatically. "On the one hand, I've been with the CBSO since I was 24 and cannot remember life without it, on the other hand I can clearly remember my trial and my first concerts as if they were yesterday.
"It was like a dream come true to get the job," Simon, son of the great choral trainer, Louis Halsey, continues. "I'd wanted to conduct a symphony chorus ever since I'd been privileged to help out Richard Hickox with the London Symphony Chorus when I was 21.
"And the job remains incredibly fresh because there is such a sense of progress over those years and because the orchestra and management have been so flexible and enthusiastic. I know of no other institution in which the chorus feels so completely a part of the whole."
Simon explains how he is "sort of" only the third director of the CBS Chorus.
"Gordon Clinton - principal of the Birmingham School of Music - did a terrific job founding the group together with the CBSO's then music director, Louis Fremaux, in October 1973, and nurturing it in its early years. He really got the choir off to a flying start.
"He was succeeded by Richard Greening, organist of Lichfield Cathedral, who died suddenly and tragically young only a few weeks into the job. After a brief period back in Gordon Clinton's hands, the chorus was then directed by Nicholas Cleobury for two years, and I succeeded him.
"At my very first rehearsal as aguest conductor, Beresford King-Smith, the chorus administrator, announced that Nicholas would be moving on in order to devote himself to the Britten Sinfonia, and I remember hoping so very much that I might have a chance to succeed him."
And he did, moulding the chorus into one of the most sought-after vocal ensembles in the world, and seeing history unfolding before him as he did so.
When the exciting Latvian conductor Andris Nelsons takes over at the helm of the CBSO in September, he will become only the third music director of the orchestra that Simon Halsey will have worked with. How does the relationship work?
"It's different with each MD," he answers. "But I have been wonderfully fortunate that Simon (Rattle) and Sakari (Oramo) have put so much trust in us, recorded and toured with us and made us feel valued. By 'us' I mean all our choruses - CBSC, CBS Youth Chorus Seniors and Juniors, City of Birmingham Young Voices - and in the future Andris will be able to nurture the new boys' choir, too."
The relationship with other conductors appearing with the choirs is a little different.
"The choirs are in such demand that Stephen Maddock, the CBSO chief executive, and I are able to build programmes in Birmingham, with other UK orchestras and abroad in such a way that we work only with conductors who can really bring something special to the choir.
"And after 25 years they're usually people I know well already because of all my work abroad. We have particularly close relationships with the BBC Phil in Manchester, and good working relationships over the years with the Halle, BBC Symphony Orchestra, BBC National Orchestra of Wales, Philharmonia, Northern Sinfonia and The Sage at Gateshead, and their principal conductors.
"I make sure the choir is prepared very thoroughly for any eventuality - and that means knowing the music and the text inside-out."
As Simon has already indicated, the chorus "family" has expanded spectacularly over the years. He charts its growth.
"Twenty-five years ago we had 125 singers in the CBSO Chorus. We then moved to Symphony Hall, and needed to grow because the hall was so much larger than the Town Hall. So now we are 182 with about 150-160 singing each concert.
"In order to improve our standards we took on a regular singing teacher (currently the outstanding Pam Davies), and a full-time administrator. Then Ed Smith (the then chief executive) and Simon Rattle allowed me to found the youth chorus (CBSYC Seniors and Juniors) and, under Adrian Partington and Shirley Court they quickly came to national and then international attention. That meant the need for a second administrator.
"Then we felt we needed a community teenagers' choir without audition in order to encourage as many children to sing as possible, and CBYV under the irrepressible David Lawrence was born and quickly got wide attention from promoters and broadcasters.
"We were always worried that not enough boys were singing so now we have funded a boys' choir under the expert guidance of Julian Wilkins. So now we need three administrators.
"And we have been lucky enough to attract a fair amount of sponsorship, notably from Barclays Wealth. Meanwhile the adults have been invited all over the world with our orchestra, and by outfits as splendid as the Vienna Philharmonic, San Francisco Symphony, Sydney Symphony, Hong Kong Philharmonic... I could go on, but the list might get boring."
And Simon is anxious to underline the importance of the commitment from the members.
"All the progress the five choirs have made over the years has only been possible because of enormous personal input by all the singers, and the astonishing way they turn up all the time."
During his 25-year tenure with the CBSC, Simon Halsey has also acquired responsibility for other choruses, and not just in this country. Busily counting his air-miles, he tells me how all the juggling is done, "with long-term and careful planning.
"I'm just coming to the end of my 11-year association with the 80-strong fully professional Netherlands Radio Choir, which required me to be in Hilversum for at least 12 weeks a year.
I'm in my eighth year as chief conductor of the Berlin Radio Choir where I have to put in 20 weeks a year and do a lot of work with Si-mon Rattle and the Berlin Phil. And I try to fly home for CBSC every Wednesday. As a result, I fly at least 200 times a year."
In fact I found myself sitting next to Simon on a flight from Amsterdam to Birmingham two weeks ago.
He'd been rehearsing the NRC during the afternoon, and was en route to Birmingham for that evening's CBSC rehearsal, before flying back the next morning.
Fortunately he lives within an easy drive of Birmingham International Airport, and still manages to lead a reasonable home life.
"You'd better check with the family - but they are all still there!" he jokes.
"Jack (18) is in CBSC and Harriet (16) is in CBSYC Seniors, and my wonderful wife Lucy spends too much time ferrying us all to the CBSO Centre."
And with his retirement from the Netherlands Radio Choir (which the Dutch turned into quite an occasion), Simon Halsey is hoping to "spend more time at home with his family".
* Simon Halsey conducts the CBSO and CBSC at Symphony Hall on Saturday at 7pm (Box office: 0121 780 3333).