The four CDs come in a slip-case the size and thickness of the average paperback measuring about 8"x5" in old money. Inside is a hardback book with two discs affixed into trays at either end. Printed on high-quality paper are the track listings, after which there is a brief essay in English, French, German and Italian on the birth and aims of the Progetto Martha Argerich at the Lugano Festival, the provenance for all these performances. Nowhere is there a word about the composers, music or artists. So far, so odd. But if ever there was (slip) case of not judging a book by its cover, this is it. This ‘limited edition de luxe set’ features nine concertos, four of which (Mozart K242, Prokofiev’s First, Bartók’s Third and Poulenc for two pianos) are new to Argerich’s Deutsche Grammophon discography, as well as her first-ever recordings of Schubert’s Divertissement, Brahms’s Liebeslieder and Milhaud’s Scaramouche. Recorded at Lugano Festivals between 2004 and 2010, none of the material has hitherto been released.

Argerich devotees will snap this set up without encouragement; others who invest in only benchmark recordings of great works will already have her playing Beethoven’s First and Second, Schumann, Prokofiev’s Third and Liszt’s First – some of her signature concertos – all of which are included here. I would not deter anyone from ‘duplicating’ because, without going through a movement-by-movement comparison, there are many moments and passages of pure delight, often deriving from the frisson of a live performance (listen to the Poulenc!). One marvels anew at such freshly minted interpretations married to the insights, subtle nuances and detail acquired only after long acquaintance.In Mozart’s Concerto for Three Pianos, co-ordination between Argerich and Paul and Rico Gulda is not always spot on but the spirit behind the performance is. I wonder whose decision it was to interpolate the theme from the Andante of K467 into the finale?

But it is disc 4, with the three ‘new works’, to which Argerich’s fans will turn first. The Divertissement à la hongroise is only the fourth work by Schubert that she has issued on disc (no solo works at all – a strange omission). Here she is partnered by Alexander Mogilevsky in an utterly captivating account from the 2006 festival. The previous year Argerich (secondo) teamed up with her friend Gabriela Montero (primo) for Brahms’s 18 Liebeslieder for choir and piano four hands. In an airy acoustic, the Swiss Radio Choir sing with ardent intensity and with marvellous precision, notably well balanced with the pianists – a feat not always engineered in many studio recordings.

The one disappointment is Scaramouche with the Austrian Karin Merle, an Argerich intimate since student days. Tempi in all three movements are puzzlingly slow – Modéré limps in at 4'48" while Brazileira, admittedly a samba, sounds terribly tired compared with the vivacious 1938 recording by the composer and Marcelle Meyer.