We speak in the middle of a travel-heavy season: in a few hours Bob will be jumping on a flight to Germany for the world premiere of The Coming, a choral-orchestral setting of three new German festive texts that Chilcott has translated into English.

‘In Germany,’ he explains, ‘they don’t have a huge tradition of new festive music like we do in Britain. But you realise that in the UK, there’s quite a generic style to the text and the way pieces present themselves in our Christmas tradition. We can be quite Christmas cliché! This German text has more angst in it.’ So, the pieces follow a progression of darkness to light, touching on how hard life can be. There’s an intensity, but ‘it’s that real human feeling to the words that I enjoy. It’s all about looking forward to the light.’

• Inside the Christmas Carol: Part One with Thomas Hewitt Jones
• Inside the Christmas Carol: Part Three with Errollyn Wallen

Germany is just Chilcott’s latest festive trip. A few days previously he was conducting his Christmas Oratorio in Poland, which also received a performance that same weekend… in Zambia! Surprising? ‘Every place brings a different energy to a piece. I think it’s the colour of the way foreign speakers sing English that gives so much life to it; I like how, when you hear someone speaking English as a second language, they speak it in a slightly different way. You don’t want a Polish choir to sound like an English choir; you want it to sound like a Polish one. The sound is bigger and heavier because their language is a bit darker; I like that.’

The Christmas Oratorio can be performed with orchestra or just organ, and the latter makes it very appealing economically to local and amateur groups. Yet, seemingly far from the universal and accessible associations of a carol, I wonder if the word ‘oratorio’ changes the nature of the challenge? ‘What I love about oratorios is there’s an extended narrative; you are trying to tell a story. I need an idea and a narrative to create something, otherwise I can’t; I love and need words.’

In the last ten years Chilcott has started writing hymns, and ‘realised it’s really hard! It must be easy to pick up and have a clear shape.’ Yet, like an oratorio, there’s a story: ‘you have to find the theatre, the context for something, otherwise it just becomes another expression of the same thing. I love the idea of finding an angle.’

One of Chilcott’s most popular festive pieces is ‘The Shepherd’s Carol’, commissioned for the TV broadcast of Carols From King’s in 2000. The theme of the service focused on the shepherds and so Chilcott was given a couple of potential texts; he chose a modern poem by Clive Sansom. He likens the words to the lyric of a Leonard Cohen song. But the space itself proved equally poetic…

‘Thinking about context and theatre,’ Chilcott continues, ‘King’s College Chapel is surely one of the biggest theatre sets in the world! It has a huge acoustic, so I thought about how I make the sounds move in that building. It should not move too fast. What also works well in that building is when the lower part of the texture has a lot of substance; it gives wings to the top of the sound. But the piece begins and ends with boys’ voices on their own; I wanted to build that into a big texture and bring it down again to show off the space we were in.’

Having been a chorister and choral scholar in that very choir, the pressure was especially acute. Chilcott admits he feared ‘they would hate it and find out I’m a complete hoax! You want to do something that reflects who you are, but then you suddenly get terribly unsure about who you are.’

It took a fortnight to compose, but the uncertainty continued. Even on the day of the performance, Chilcott was convinced it would be cancelled! ‘There’s an incredible lack of confidence I have on a daily basis. You want to do your best work, show yourself, be yourself. The piece must communicate something that’s honest.’

King’s College Chapel was a space Chilcott knew well long before composing for it, and we ponder what he learned about the construction of a good festive piece from his other perspective as a singer.

‘I learned about how beautiful a legato expression can be, because we sang in a building that was so forgiving; but at the same time, you had to work very hard to make the textures clear. When I was a chorister and choral scholar, we didn’t have the annual tradition of a commissioned carol; Stephen Cleobury started that.’

‘I remember singing a lot of William Mathias, pieces that worked so well in that building because they had a lot of clarity. I learned a lot about that; how to make energetic textures without too much superficial clutter getting in the way. A building like that is a great teacher. New pieces that worked well in that space had energy, strong rhythmic impulses and clear lines. In a way, that’s key for any building; it’s about having clarity of idea.’

Mathias’s ‘Sir Christemas’ is a particular favourite, and Walton’s ‘Make We Joy Now In This Feast’. Their energy and mobility of textures leapt out at him, with voices moving fast but always clear.

Chilcott sang stalwarts of the festive repertoire too, including the opening treble solo of ‘Once In Royal’ in 1965, 1966 and 1967. He distinctly remembers David Willcocks advising him to imagine the audience as cabbages, to calm the nerves. It worked – Chilcott says he was pretty calm in the moment – but he points to the daunting challenges of the melody: ‘we sang it in G major, so it would go D, F#, G – and by the time you’re singing ‘Mary was that mother mild’, you’re singing a top E. It’s not a high note on its own but is in that context. It’s very hard.’

Willcocks, he remembers, was a stickler for good pitch. ‘If it was flat, you could see him going berserk in his mind! He was quite a tough choir director, a hard taskmaster, but he made you feel confident. We really respected him because we knew his incredibly high standards were never about him, but about what we were doing.’

Helpfully for the future choral composer, Willcocks was also very text driven. The articulation of consonants, Chilcott remembers, was especially strict. This was vital in an acoustic like King’s, because without strong consonants, the words wouldn’t be heard. ‘We learned,’ Chilcott adds, ‘to work that building.’

Exploring Chilcott’s favourite traditional carols, he points to the multilingual classic ‘In dulci jubilo’. ‘What I love about it is the atmosphere. It’s steeped in the tradition of Mendelssohn; there’s a clarity in the way Pearsall arranges it. It’s beautiful to sing; any part you have – even a filler part – is strong and you understand the context of why you’re not taking the melody.’

His other favourite is shared by Thomas Hewitt Jones in Part 1. ‘We sang the premiere of Elizabeth Poston’s “Jesus Christ The Apple Tree”. It’s so simple in its expression yet so strong. It’s difficult to sing as it has a big range – an octave and a fifth – but the great thing is it’s written so that you always hear the words. It’s all about the text. Those things really made an impression, but it’s not maybe until later that you realise why you loved those pieces as a child. There was something about it that made you understand composing.’

The recurring carol ingredient Chilcott spots is ‘a good tune’. He describes refrains as ‘very sociable’, likening it to how most people remember only the chorus of a popular song like ‘Over The Rainbow’. A carol is, after all, about accessibility.

But that doesn’t mean they’re all rosy (spotless or otherwise). Chilcott suggests that as time has passed, there has been an increasing focus on text, and gnarly ones at that. This makes him particularly excited about new words in carols: ‘there’s an element of cliché in the way that we perceive Christmas. It’s often expressed in a “Gloria in excelsis Deo”. I’m inspired by approaching something which is so well known from a different angle; new expression of something familiar is key.’

But surprisingly for one of the world’s most celebrated choral writers, Christmas is not a time for huge singsong at Chilcott HQ. In the esteemed composer’s words… ‘We’re very dull!’

His father-in-law was Philip Ledger, Director of Music at King’s. ‘There was so much emotional connection to the carol service,’ he admits, ‘there was a sense of “get it over with”. Too much stress! Come Christmas, you’re knackered!’

So, Chilcott’s modern family tradition is to visit their local green and sing carols; as far as King’s is concerned, he doesn’t attend the service regularly. ‘We like our local efforts – lots of out of tune singing!’ Plenty of heart – and lungs…