In this case the key is A flat major. Jean was playing the piano while waiting for the arrival of our grandchild for a morning of joy. She started playing the A flat major slow movement of Beethoven’s Pathetique Sonata. Not unexpectedly I heard it in A major. I repeated the experiment I have chronicled before: I came up next to her and looked at her fingers playing all the flats and my sense of the key change back to A flat major without any change in the actual sound.

Two days later we were privileged to attend a piano recital by David Earl. First on his list was that Pathetique Sonata. It is in C minor which has remained (so far) one of the strong keys for me. So the first movement was thoroughly satisfying in this questing minor key. I wondered what would happen to the slow movement. I needn’t have worried – it was wonderfully held in A flat major even after the intrinsic modulations that Beethoven incorporates, right through to the gentle chords at the end. And of course the Finale stayed in C minor always through.

David Earl follow the Beethoven with some Chopin Impromptus. The first one was the A flat major one which carried on the tradition of sounding in the key. The test came with the F sharp major Impromptu. F sharp major is a weak key, and I fully expected to hear things in G major, a semitone up. This did not happen until the key changed in the D major central section. Things went awry at this point as D major rapidly shifted into E flat major which it tends to do these days. And from then on the the rest of the Impromptu was in the wrong key. And the C sharp minor Fantasy Impromptu which followed did something most disturbing: it started in D minor and the middle section was in D major. This totally altered the feeling of the piece, disappointingly. It almost made a nonsense of it.

Schumann’s Carnaval was to come in the second half of the recital. This is entirely in flat keys with A flat major as the base key. It is one of my favourite musical suites and I have enjoyed playing it to the best of my ability on the piano. I know how the pieces feel under the fingers. So when David started playing in what seemed to be A major, I thought I would be in for over half an hour of further disappointment. However as the first section was coming to an end, I saw his finger playing a white note where A major would have had a black note. And miraculously the music transmuted back into A flat major. Every one of the miniatures from then on was in the correct key and I had a wonderful Carnaval experience.