John Wilson switches between two conducting hats whenever he visits Symphony Hall. Sometimes he appears on the podium conducting the CBSO in programmes of predominantly English music; at other times he bewitches the hall with sounds of the Hollywood silver screen and Broadway.

And on Sunday, November 23  it’s the showbiz hat he is wearing, when he brings his own amazingly expert John Wilson Orchestra back to Birmingham for a mouth-watering evening of Cole Porter in Hollywood, featuring some of the most bewitching numbers ever written by any composer of vocal music.

Warner Classics has recently released a CD with the same title, a taster for the live concert (and a memory to treasure), and the amazing sound of the orchestra, hand-picked from some of the finest musicians in the country, but who can only rarely get together.

“We’ve been playing together for almost 20 years now and a great many of the players have been with us for a lot of that time and some key players (leader, drummer, lead sax) have been in the orchestra from day one,” explains John.

“And during that time we have, of course, all developed as musicians but the actual style of the orchestra hasn’t changed at all. We all know what we’re aiming for and that helps forge the sound of the JWO.”

John has famously excited everyone’s awe and respect for his painstaking reconstructions of lost film scores which had been deliberately jettisoned as part of an economic drive by MGM Studios. He worked from surviving orchestral parts, and brought everything back to life. The technique applies to the arrangements used in this Cole Porter programme.

“They’re not my own arrangements, but very often they’re my reconstructions of the original arrangements of these songs and orchestral works,” he explains.

“I stress original because that’s the cornerstone of what the JWO does – we don’t play new arrangements of old songs – the whole point of the JWO is to present this material exactly as the composers and their original orchestrators wished to hear it.

“One wouldn’t go to the opera and accept somebody’s re-orchestration of The Marriage of Figaro – I feel the same about My Fair Lady. The composer and orchestrator gave us a beautifully crafted work of art and it is up to us to present that to the public as it was originally conceived.”

I wonder if John Wilson’s immaculate conducting technique (he won prizes during his student years at London’s Royal College of Music) contributes to the efficiency and success of his necessarily few rehearsals with his JWO.

“I’ve been doing it a long time and I had a top class teacher in Neil Thomson. I think conducting repertoire outside of light music is crucial to the success of making the JWO sound – I hope I bring something of the discipline of conducting symphonic repertoire to this music.”

John also holds separate voice rehearsals before introducing the vocalists to the orchestra.

“Luckily, the singers we work with are stylists, know what’s needed, and always turn up off-book and thoroughly prepared,” he explains.

He talks in detail about the great show-tune writers.

“All of the ‘big six’ (Irving Berlin, Jerome Kern, George Gershwin, Cole Porter, Richard Rodgers and Harold Arlen) have their defining characteristics,” he says.

“Berlin pretty much created the American popular song – certainly he was the first to really capture the essence of the vernacular in song, and Kern built on that and added a European polish in to the mix.

“Gershwin was the only composer of them all – the others were brilliant songwriters – who could write real music across most genres, and this skill, allied to the most fecund musical imagination, gives his songs an unrivalled depth and quality. Porter, you may argue, succeeded more than anyone in marrying words to music; his own words fitted to his own tunes, as if they were all conceived of a piece. And what brilliant lyrics and ballad tunes of great yearning and depth of feeling!

“Rodgers was the most innately talented of them all, All of his songs are good, some of them great. And he could write across the widest range of styles, from the Tin Pan Alley hits of the 20s to the almost operatic dimensions of Carousel. Arlen – the least known – is considered by many to be the best of the lot.

 He didn’t know how to write a bad song and the jazz-infused songs in the Arlen catalogue sound as fresh as the day they were written. They have a melodic and harmonic sophistication that is hard to find elsewhere. And The Man That Got Away might be the greatest popular song ever written – I think so!”

With his gifts in every genre of orchestral music, plus his communication skills, I suggest that John might conduct a mean Last Night of the Proms at the Royal Albert Hall. His reply is typically modest.

“The BBC Symphony Orchestra are very lucky to have a conductor of such skill and style as Sakari Oramo. They certainly don’t need me when they have him!”

John Wilson and his Orchestra are at Symphony Hall on November 23 (7.30pm). Details on 0121 780 3333.