There are certain aspects of being an orchestral musician which can appear baffling to an outsider especially the collective sense of humour. A fair amount of this is based in orchestral “traditions” – responses to comments, events or musical moments – which have been passed down the generations of players and while each orchestra might have its own set of these there are several which seem to be common to most orchestras.

Tonight the BBC Concert Orchestra is pre-recording a Friday Night is Music Night tribute to Gene Kelly in the wonderful Hackney Empire. The presenter is West End and TV star John Barrowman, no stranger to working with orchestras, but he was completely floored by one of the most common of our “traditions” in rehearsals yesterday, amazed and highly amused by something which is by now common instinct and a standard reaction even to the newest recruit in the orchestra.

We can feel it coming and know that in every programme which celebrates Musicals from stage or screen there will be what is technically called a “Stop Chorus”. This is where the orchestra or rhythm section only plays the first beat of each bar for 8 – 16 bars, the rest being filled by the wonderful sound of highly skilled tap-dancing. In the percussion parts we often spot this well in advance as it will usually fall to us to play an elaborate rhythm on a woodblock , offering a hollow imitation of the real thing, however some arrangements come along deliberately leaving the gaps empty in case there is an available guest performer who can actually tap dance for real. When reading through an arrangement for the first time and coming across such a moment, by beat three of the first empty bar the entire orchestra will be stamping their feet wildly as fast as possible without any attempt at specific rhythms, giving the impression of a highly unskilled herd of tap-dancing hippopotami! This is exactly what happened as we read through an arrangement of “I Got Rhythm” in rehearsals yesterday reducing John Barrowman to helpless laughter – he found it so funny he even asked us to keep it in for the show!

However it is an in-joke and while the audience in the theatre might enjoy the visual surprise, the listeners for the broadcast would be left completely baffled, so after discussion I had with conductor Larry Blank and the producer we’re reviving a little percussion section party-piece which was created for a Prom a couple of years ago.

I know that many percussion players have tried to come up with a better tap dance alternative to the humble wood block and eventually taken perhaps the most obvious route – real tap shoes held and played on a horizontal wooden board. We’ve certainly done this in the BBC CO, but while this achieves the right aural effect, the visual element isn’t usually seen by most of the audience. For the Royal Albert Hall we took this to a new level – the black wooden boards were positioned vertically behind the percussion section and at the stop chorus in the arrangement (42nd Street, naturally!) all six percussionists turned round and crouched down while playing the white tap shoes, mounted on sticks, above our heads. We even had black cloth fitted to the sticks which covered our hands so that the white shoes stood out against the black boards. I had to get hold of several more pairs of tap shoes for this and got them from a company called Dancemania who enjoyed helping make this happen so much that they created their own blog http://www.dancemania.biz/blog/white-tap-shoes-at-the-royal-albert-hall/ all about it which contains photographs, rehearsal video and an audio clip of the moment itself together with the reaction from prommers and the presenter, Katie Derham.

Before the rehearsal this afternoon we’ll rehearse our tap dance moment (just three of us this time) and the sound engineers will make sure they get the best sound for the listeners and hopefully the audience and John Barrowman will enjoy the visual surprise as well. I’ll have to wait until the broadcast to get an audio clip of the piece but once I have one I’ll post it here.