As part of his duties as Cantor of St Thomas’ Church in Leipzig, Bach was required to compose settings of the Passion of Jesus Christ for performance on Good Friday. He found the task a chore, though the two that survive in frequent performance today (St Matthew and St John) give the appearance of anything but, though both, as was the order of the day, contain some self-borrowings.

In fact Bach wrote five Passions, of which the final one is that according to St Mark, to a libretto compiled by the composer’s principal librettist Picander, and performed on Good Friday, March 23 in 1731. Its appearance had involved the recycling of music from earlier compositions (Bach was not alone in doing this; “For unto us a child is born” in Handel’s Messiah was an exact transcription of sexy love-duet “No, di voi non vo’ fidarmi” from the composer’s pen), and was achieved with the minimum of effort in what was a disruptive period in Bach’s life in connection with his employers and premises.

Bach also took ideas from a slightly earlier setting of the St Mark Passion by Reinhard Keiser, of which he made two copies (think about it: restricted daylight in northern Germany, and working by candlelight during the long evenings; no wonder Bach had to undergo eye surgery).

There is a legend that a score of the St Mark Passion existed, but was destroyed as the result of a bombing raid in World War II.

Whatever the case, a putative reconstruction exists, and will receive a rare hearing when the Birmingham Bach Choir performs it in Lichfield Cathedral on Saturday. Paul Spicer, conductor of the choir, tells me how this unique event came about.

“I was first put on to this new reconstruction when I met Andor Gomme at the Bishop of Lichfield’s house about ten years ago. He told me about this new edition he had put together and which Barenreiter had just published. It sounded fascinating and just the sort of thing which needed to be investigated. He was involved with the Keele Bach Choir and they had participated in the experiment of the re-creation of this long lost work. I performed it in 2007 with the Whitehall Choir in London and it proved to be a fascinating glimpse into something which might have been. What really interested me was how very different this Passion was from the Matthew or the John – and, of course, these two works are very different from each other.

“The great thing is that in performing this Passion we are given an opportunity to sing something different at this time of year much of which is by Bach and which will make people understand further Bach’s extraordinary creative life. It is also a fascinating detective story! The performance of this work is exactly what the Bach Choir should be doing, and is of course entirely in the great and long tradition of this wonderful group which I’ve now been conducting for 25 years!”

Most of the Birmingham Bach Choir’s performances are given in Birmingham, either at Symphony Hall or in the Cathedral. Why has Lichfield been chosen for this very special event?

“There’s no easy answer to this, but the Bach Choir does go to sing in Lichfield quite regularly given my very close associations with the cathedral (I am now a lay member of its Chapter). Somehow, also, performing a work like this in a great Gothic space gives added quality to the feel of the experience,” Paul explains, before going on to tell me about the forces required to perform the St Mark Passion.

“The forces are modest, like the St John. Flutes, oboes, strings (including violas da gamba) and continuo, plus the usual group of soloists and we are particularly thrilled to have Thomas Hobbs back with us as our Evangelist, one of the best around at the moment.’’

And Paul concludes in a huge burst of enthusiasm for his work with the Birmingham Bach Choir.

“I’d just like to say what a joy and a privilege it is and has been for the last 25 years to conduct this great group which I believe goes on getting better and better. When Richard Butt retired from the choir, having conducted it for 25 years, I wondered how anyone conducts a choir for that long.

“Now I know, and I have no intention of retiring yet, feeling that if the relationship works and I still have lots of energy and a desire to investigate new repertoire and keep the choir on top form then there is no need to hang up my baton yet. I hope this performance will be another step on the ‘forward’ path.”

* The Birmingham Bach Choir performs Bach’s St Mark Passion at Lichfield Cathedral on March 11. (7.30pm).

Upcoming Concerts

* March 9-11: Birmingham Conservatoire presents Mozart's opera The Marriage of Figaro at the Crescent Theatre, Sheepcote Street (March 9 and 10, 7pm, March 11 2pm and 7pm).

* March 10: Cellist Razvan Suma and pianist Rebeca Omordia perform sonatas by John Ireland and Georges Enescu at the Birmingham and Midland Institute, Margaret Street (1pm, admission free)

* March 14: Jennifer Pike performs a celebrity violin recital (Mozart, Szymanowski, Vaughan Williams and Wieniawski) at Birmingham Conservatoire (1.05pm)