Traditional August Bank Holiday weather – steady rain – was reflected in the melancholy programme for this lunchtime Chamber Prom. From the famous Adagio of Samuel Barber’s String Quartet to Shostakovich’s lugubrious Piano Quintet, an atmosphere of gloomy introspection pervaded Cadogen Hall, populated by a steaming, sodden audience. Breaks in the musical clouds occurred via the sarcastic Scherzo in the Shostakovich and through Debussy’s Feux d’artifice, which briefly lights up the keyboard before fizzling out into a damp squib.

It’s always good to hear Barber’s Adagio in its original string quartet form, even if it was shorn of its context here. As is their practice, the Emerson String Quartet stood to perform, with Paul Watkins seated on a riser so high that he was at head level with his colleagues. Where massed strings can lend the Adagio a glutinous quality, here it was lean and clean, with minimum vibrato, but a warm, caressing cello line.

After the Emerson’s entrée, it was Elisabeth Leonskaja’s turn for a Debussy palate-cleanser. Feux d’artifice, a pianistic depiction of Bastille Day pyrotechnics, allowed her to demonstrate a lively palette of colours and dynamics, from a crystalline upper register to grumbling bass.

Shostakovich provided the main course. His five movement Piano Quintet was composed two years after his String Quartet no. 1 in C major, at the behest of the Beethoven Quartet. It is almost neo-Baroque in form, with a long second movement Fugue following the Prelude. At times, it’s as if Shostakovich has pitched the piano against the strings: the work opens with a long piano solo and at times the piano seems to provide a commentary on the string quartet’s contributions.

There is something stately and regal about Leonskaja’s presence at the keyboard. She is pure “Russian Old School” – she knew Shostakovich himself and was a regular duet partner of Sviatoslav Richter – and her sound is magnificently Herculean. At times, it can be a little unsmiling; the Scherzo’s clangourous contributions missing some of the fleet-footed wit, even if it is largely tongue in cheek. But Leonskaja brings an authenticity about her Shostakovich which was a privilege to hear.

I’m more ambivalent about the Emersons. They play with great unanimity of attack and their playing is big-boned and uncompromising. Cellist Paul Watkins is the newest member of the line-up. Formerly of the BBCSO and the Nash Ensemble, he brings two very welcome qualities to the quartet: warmth and a keen sense of communication. He is the focal point of the group, eagerly inviting the other members into musical discourse, emotion written over his face (just as when I reviewed him with the Nash Ensemble last autumn). Apart from Lawrence Dutton (viola), however, Watkins received very little back. Both violinists (Eugene Drucker and Philip Setzer take turns to lead) were decidedly icy in terms of platform manner and, in Setzer’s case, glassy tone. Very little eye contact was offered at all during the Quintet.

The playing was at its most beautiful in the Intermezzo, pizzicato cello and piano crotchets repeatedly dripping against the window pane beneath the poignant first violin line. Some welcome joy came from the Scherzo-Furiant from Dvořák’s sunny Piano Quintet, Op.81, as an encore. Outside, even the rain momentarily ceased.