Photograph: BBC/Adrian Weinbrecht

Three hundred years ago, J S Bach and Louis Marchand, generally considered to be the two leading keyboard players and organists of the age, were scheduled to take part in a play-off in Dresden to determine who was number one. But the competition, to be based on improvisation skills, never took place, since Marchand failed to turn up: apparently he was homesick and had had to return home immediately.

Whether this challenge really took place is uncertain, since few details of the alleged competition have survived. It was, however, a good starting point for one of the concerts in this year’s Lufthansa Festival of Baroque Music: a recital by the distinguished American organist Kimberly Marshall on the Klais organ in St John’s, Smith Square. Called Bach versus the World and part of an overall festival theme (appropriate to Olympic year) of ‘Contests, Competitions and the Harmony of Nations’, it can be heard on Radio 3’s Early Music Show (6 October), together with an interview with Marshall conducted by the singer and presenter Catherine Bott.

‘She’s a very significant artist,’ says Bott. ‘Female organists of her stature, particularly with her interest in early repertoire, are comparatively rare. As well as being a fine player, she’s a thoroughgoing academic musician who took her doctoral thesis – on the iconographical evidence for the late medieval organ – at Oxford.’ Marshall’s programme opens and closes with Bach, while in between come pieces by Marchand and the pioneering medieval organist Arnold Schlick.

Bott’s interview with Marshall was unscripted. ‘Some of my favourite interviews are those when I just sit in the studio, obviously with a structure but no scripted questions. My job is to make sure I give the production team who edit the programme, questions that are sensible, produce eloquent answers, and particularly answers that come to a natural end. One has to make sure that you stop eager and knowledgeable guests from telling you everything they know.’

It’s been nine years since Bott joined the Early Music Show as a writer and presenter, sharing the duties with Lucy Skeaping. Since then, she’s presented more than three hundred shows and has made such an impact that many listeners think she has given up singing. ‘It isn’t true. I’m actually in rather good voice at the moment so do spread the word one’s vocal chords haven’t actually collapsed.’

What Bott likes particularly about the programme is that it covers such a wide area, and even after nine years on the show she is still making new discoveries. ‘It’s a niche programme but my goodness what a niche! I recorded three programmes yesterday. I talked to Benjamin Bagby about Icelandic sagas for a programme in November, moved on to interview Fiona Maddocks about Hildegard of Bingen, who is finally being declared a saint after a canonising process that seems to have lasted for more than five hundred years, and did a simple script-and-read for a concert commemorating the 400th anniversary of the death of Gabrieli.’

One of the perks of the job is, Bott admits, getting to meet remarkable people like Marshall. ‘She was, like the vast majority of musicians, a delightful guest. She was humorous; she’s got a lively personality and a lively wit. It was such fun to meet her. She’s good news all round.’

The Early Music Show is available on iPlayer for seven days after broadcast.