There’s something compelling about hidden places, and of all the recording venues in the UK, Potton Hall in Suffolk has to be one of the more difficult venues to find. As you head east and the countryside flattens out, the sky expands, its colours taking on a more dramatic hue – an apocalyptic pre-snowfall red and bronze on this particular February afternoon. The entire area is redolent with musical history – not only Potton Hall itself, built to house its original owner’s eccentrically sizeable organ collection, but Aldeburgh itself is only a few miles away, scene of those legendary duet collaborations between Benjamin Britten and Sviatoslav Richter. I remind myself of these on the drive over: it’s playing full of passion, with the heat of the moment more important than perfect technical finesse.

In session are two rather quieter stars of today’s pianistic firmament, Paul Lewis and Steven Osborne, born just a year apart. Lewis’s Schubertian credentials need little introduction, as anyone who knows his compelling sonata recordings for Harmonia Mundi will attest. But it was in fact a project of Steven Osborne’s, exploring late Schubert across different genres, which prompted these Hyperion sessions.

As I arrive, they’re in the midst of the A flat Variations. What’s immediately noticeable is the sheer beauty of sound, the delicacy that they’re achieving, Paul playing primo, Steven taking the secondo part. It’s a far more inward, sheerly beautiful reading than that of Richter and Britten, caught live in the '60s. That they’ve already given several concerts of these works clearly shows: Paul in particular seeming very calm, Steven perhaps a little edgier.

They swap places for the B minor Variations – a work that absolutely deserves to be up there with the other more famous Schubert duets, extraordinary for the way it grows from an unassuming idea, and the far-reaching emotional landscape packed into its short span. Each take is done with complete concentration, and the level of playing is astonishingly high. Not always high enough, though, for these self-critical artists: ‘My flabby instincts got the better of me,’ Steven laughs at one point. And they play it again, still better.

The following morning it’s the turn of the F minor Fantasie. Steven, who has returned to the lower part points out ‘I’ve got about two bars to practise; Paul has loads’. While engineer Simon Eadon is fine-tuning the technical set-up, the pianists vamp around with the opening theme: at one moment Prokofievish, now bluesy. They may be quite different studio animals but musically they clearly share a profound kinship. When they get down to business, they take the Fantasie at quite a lick. Producer Andrew Keener points out the timing is 18’28”. Could this be a new concept in interpretation, basing timings on the year a work was written? Such spontaneous moments punctuate these sessions, which are intense yet never tense.

You’re reminded just how subtle and treacherous a work the F minor piece is – the repeated right-hand notes arguably as difficult as the opening of Beethoven’s Fourth Concerto. And then there’s the fugue; the producer may be happy after the first take, but the pianists aren’t. ‘A bit more talented’ is Steven’s typically dry response. But by the third complete take things have settled, the fugue now possessing tremendous power but without opaqueness. ‘That’s quite overwhelming, guys’, says Andrew. He’s right.

Of course there are great recordings out there of Schubert’s duets: the aforementioned Richter/Britten and, more recently, Perahia/Lupu, Eschenbach/Frantz and Pires/Castro. But, established duet partnerships aside, it’s relatively rare to find two leading soloists sharing a keyboard. Paul explains, ‘The traditional view of the duets has been that they display the gemütlich aspect of Schubert but that’s not the case at all. The F minor Fantasie is very difficult musically and demands a lot of time and attention – which is something soloists tend not to have.’

Presumably there’s also the whole question of pedalling. ‘Yes, that’s a major point for every professional pianist because it’s one way we use to get our own individual sound. So you feel a bit naked if you’re not the one controlling the pedalling in a duet but even if you are, that feels weird too as you’re not pedalling just for yourself.’

‘Another aspect is, of course, having only half the keyboard!’, points out Paul, though there seems to be plenty of give and take, with the two artists switching round and therefore taking turns with the all-important pedalling. Steven confirms this. ‘We are great friends and laugh a lot together – which means everything when you are rehearsing. Of course there were various things we disagreed about but when you respect someone’s musicianship you take it seriously when they don’t like what you’re doing. If we disagreed, we would try out different things and often find some kind of compromise: it felt to me that the process accentuated our strengths and mitigated our weaknesses.’

So is there more to come from this quietly compelling partnership? Very possibly, but we’ll have to wait till 2014, when the two artists should be dishing up the double concertos of Mozart and Poulenc: a delectable prospect indeed.

Harriet Smith

Schubert Piano Duets, performed by Paul Lewis and Steven Osborne, is released by Hyperion Records - buy from Amazon