You usually sing heroes that are quite loud and full of themselves, but now you’re doing a prisoner. What attracts you to the part of Florestan?
In my eyes Florestan is a heroic figure, because he’s been broken. He keeps faith with the political convictions that landed him in jail, displaying moral fibre and retaining his dignity in the face of great adversity. His message is that ideals are worth fighting for. And the idea of doing everything in your power to defend certain values and beliefs – even to the point of prison or capital punishment – is acutely topical. Think of the risks women are taking in Iran at the moment. Hats off to them.

Your Wagnerian heroes are often saviours, but now you’re playing someone who’s being rescued himself – and by a woman, to boot. What are your thoughts on that?
Doesn’t bother me at all. Being rescued is nice!

What’s the bit in FIDELIO that you like singing most?
I like his aria. It covers a lot of ground. Florestan starts off in a desperate mood, switches to abject sorrow and resignation, is overtaken by euphoria - and then plunges into desolation. I get a big kick out of covering that range of emotions - especially early on in the fast stretch, when he sings “Und spür ich nicht linde, sanft säuselnde Luft”. I love rendering that burgeoning ecstasy in song.

The jailed Florestan is close to death by starvation. How do you reflect that sapped strength in song?
It’s Beethoven’s music, not the way of singing him, that expresses his physical condition. I take my lead from the music. Take the end of the aria: it’s suffused with resignation and ecstatic sadness. What I’m doing is just enhancing all that with some superimposed despair and hopelessness.

Florestan is a small role. He doesn’t make an appearance until the end. Is that good or bad for you?
It always seems to me to be over in a flash, but to be honest I quite like that for a change! Obviously the part is challenging in its way. It’s very compressed, so there’s no gradual feeling my way in; I have to hit the ground running. And it’s all over just as fast. It’s full-on action.

The difference between Wagner and Beethoven?
FIDELIO is the only opera Beethoven wrote, so if we’re comparing him with Wagner of all people, that’s a big difference. As for difference in form, he gives us polished, complete numbers, whereas Wagner writes ‘through-composed’ operas. And unlike Wagner, Beethoven repeats lines and phrases. But the big difference for me as a singer is that Beethoven is ultra-classical and Wagner’s a Romantic. A Classical opera has to be sung with more precision. Timing and meticulous vocals and the interplay of voices are everything. With Beethoven, if one of the singers or musicians isn’t bang on target, then you end up with a dog’s dinner.