On Saturday, I shall be playing Mozart’s last piano concerto  – the B flat major, K595 – with the Meadows Chamber Orchestra in Edinburgh. Since I don’t have an in-house orchestra, I have been preparing by playing along with a recording. We have three CDs in the house – two played by Clifford Curzon (different years, different orchestras and conductors) and one played by Arthur Schnabel.

It’s very interesting to play along with someone else’s recording. You might think that as we are playing the same notes, it would be easy to synchronise, but in fact it is a slippery matter. First of all, the other person’s choice of basic tempo may be slightly different from mine, and it’s surprisingly difficult to settle to a tempo which doesn’t feel quite right under the hands. Mozart did not supply metronome marks (he never knew the metronome), so his ‘Allegro’ and ‘Larghetto’ are all we have to help us.

Even when we agree on the tempo, I find that the other pianist and I ‘come apart’ in almost every bar – whether just for half a beat, a beat, or more. There must be thousands of tiny differences in the way our fingers move from one note to the next, or in the minuscule ‘breaths’ between phrases – and these discrepancies mount up. I seem to start in harness with my unseen pianist companion, but by the time we get to the end of the section, I’m ahead.

At least, that’s how it is in the case of Clifford Curzon, who had a thoughtful, measured approach to this concerto. I know he liked to practise with a metronome, to ensure reliability.  When I play along to his records, I keep getting ahead of him (I suppose I must be rushing).

By contrast, Arthur Schnabel is mercurial. He often gets ahead of me, especially in the last movement. Yet in the slow movement he takes a tempo so slow that I can hardly bear to play along with him. I puzzle over how the same person can feel at home with a slow-as-treacle Larghetto and then suddenly sprint ahead of me in the finale with devilish virtuosity.

On the whole, I feel Brahms had the last word about the metronome: ‘I myself have never felt that my blood and a mechanical instrument go well together’.