Think of 18th-century Requiems and one name inescapably springs to mind: Mozart. His unfinished masterpiece is possibly the earliest setting of the Mass for the Dead to have entered the regular repertoire, where it reigns supreme over later settings by Berlioz, Verdi, Fauré and Britten. The casual listener might be forgiven for imagining that this monumental tradition sprang as if from nowhere in 1791; those who read their CD booklets deeply will be aware of the C minor work by Michael Haydn (1771); but before that, you have to go back beyond the Baroque to find Requiems that have any currency in the 21st-century concert hall.

Of course there was a tradition of Requiem Masses in Catholic Central Europe, however, albeit one that is largely now obscured from view. Nevertheless, there are still some brave pioneers eagerly lifting a candle to the murkier recesses of Habsburg-era archives and making some startling discoveries. One such is Nicholas Newland, director of The Amadè Players. He has devoted the past decade to unearthing some of the plethora of works by Johann Waṅhal, a slightly younger contemporary of Haydn, and the results of his painstaking work will be heard next Tuesday at St John’s Smith Square. Along with a double violin concerto by Dittersdorf and a horn concerto variously attributed to Haydn among others, he will direct the first modern performances of a symphony in A minor and an E flat Requiem.

‘He wrote two Requiems,’ Newland tells me in his office at Goldsmith’s College. ‘This is the quirky one, with no violas but two horns. It’s a perfect example of all the things that give Waṅhal a unique accent as a composer.’

Newland doubts Mozart would have heard this Requiem but it nevertheless demonstrates that there was a continuing need for devotional mourning music of this type. The second, larger and more richly scored Requiem, however, probably dates from 1784, when Mozart was in Vienna. Given Waṅhal’s fame in the Imperial capital at the time, it’s possible that Mozart would have been aware of this more imposing work.

‘The two Requiems are supposed to have been written for his parents. This one is earlier: there is no firm date but my best reckoning is that it comes from 1774 to 1779. If you were going to draw a line and say there was a “mummy Requiem” and a “daddy Requiem”, then this is undoubtedly the “mummy Requiem”. It’s tender and lyrical, less experimental than the symphonies. The shortness and the scoring of it feel very much as if he’s getting in touch with his past in the church, unlike the forward-looking second Requiem, which is far more Viennese in style. There’s a simplicity far removed from his symphonies and all the Sturm und Drang that comes in later.’

Waṅhal is perhaps best known nowadays as one of the partakers in an extraordinary quartet evening in Vienna, in which he played alongside Dittersdorf, Haydn and Mozart. The young Salzburger also performed one of his violin concertos – before he had begun composing his own – and wrote in glowing terms about it to his father.

So why isn’t Waṅhal’s music better known? ‘There is a big argument that revolves around the German domination of musicology in the 19th century. Also, Waṅhal was far more aligned in age and style with Leopold Mozart and Haydn than he was with Wolfgang – a sort of halfway bridge between Leopold and Wolfgang.

‘If you put this Requiem up against Mozart’s, of course it doesn’t hit the public as hard. But it wasn’t intended to: it was written for a mother or a father, for a single small performance. I think it serves its purpose beautifully, while Mozart’s is a totally different kettle of fish, so I think the comparison is unfair.’

Waṅhal’s neglect since his death may be put down to rumours of mental instability, which appear to have started with the contemporary diarist Charles Burney. ‘Waṅhal did spend time out of the public eye,’ acknowledges Newland, although he sounds a cautionary note. ‘Whether it was in an asylum or in a church there is no proof. What was actually the case is that he was a very modest man: he didn’t sign his manuscripts; he didn’t spend a lot of time promoting himself. I think as the symphony developed further, it was his fame that did the damage. The idea of him being mentally ill today would be most likely be recognised as stage fright.’

A look at the score of this E flat Requiem reveals a cantabile lyricism that also imbues some of his symphonies. There are familial relationships between the themes of the brief movements and prominent parts for the pair of horns, but it is choral and homophonic throughout, with no solo moments – a far cry from the imposing contrapuntal monumentality of Mozart’s much later Requiem. All the same, it is a reminder that such music was continually required and continually performed. To the modern music lover it may appear that the Mozart was the founding work of the dramatic Requiem tradition that carried on through the 19th and 20th centuries. But Waṅhal, along with his contemporaries, deserves a hearing. Next Tuesday’s concert is a valuable opportunity to do just that.

The Amadè Players perform Waṅhal’s Requiem and A minor Symphony, along with a double violin concerto by Dittersdorf and an anonymous horn concerto attributed to Haydn, at St John’s Smith Square on Tuesday 31 March at 7.30pm. The repertoire is being recorded for Resonus Classics, due out in August.