"A genuine discovery for everyone," is how violinist Matthew Trusler describes William Mathias's Violin Concerto, a work that for some years has languished in comparative obscurity. Written to a commission from the Hallé in Manchester, it was completed in 1991, shortly before Mathias's untimely death from cancer, and dramatises an existential battle with mortality that opens with a long, weirdly unbalanced lyrical melody and closes with a defiantly aggressive rondo. In between comes a wild scherzo and a ritual lament, at times reminiscent of the slow movement of Shostakovich's Leningrad Symphony.

It's not a masterpiece: the first movement meanders, and there's an awkward dip in pressure at the centre of the lament. But it was a tour de force for Trusler, who gave the concerto its long-delayed London premiere at the Proms, alongside the BBC National Orchestra of Wales, with Mark Wigglesworth conducting.

Trusler brought an organic ebb and flow to Mathias's twisting melodies. His handling of the rondo and the work's big cadenzas was thrillingly dexterous. The orchestration veers between opulence and abrasion: Wigglesworth did wonders with it. Both he and the BBCNOW are on tremendous form at present.

The concerto was flanked by Wagner's overture to Das Liebesverbot, and Elgar's First Symphony. Wagner's early take on Shakespeare's Measure for Measure was written with an eye to international success, and the overture, glitteringly done, sounds like French camp until some portentous Rienzi-style fanfares remind us who wrote it. Elgar, meanwhile, claimed his First Symphony embodied "great charity (love) and hope in the future". For Wigglesworth, conducting from memory, the symphony is something altogether more troubling – a work with deep turmoil at its core, in which both tranquillity and exaltation must be fought for and won. A powerhouse performance of great integrity, it was superbly played and often overwhelming in its impact.

• The Proms continue until 13 September. Details: bbc.co.uk/proms