But the old man didn’t flinch. A pipsqueak laugh escaped from the strange mask. ‘They took my most precious assets long ago, my dear!’ he piped. ‘More years ago than I can count!’

‘Blimey!’ said the Doctor. ‘Is that was this is all about?’

‘Of course not!’ hissed the old man. ‘Evviva il coltello! Long live the knife! It was a blessing that took them away. A wonderful blessing! I was the greatest of the Castrati! The noblest of callings. The purest, most angelic sound known to man. None could match me. Until that ape Mazzini declared our sacred order must end!’

Then he kicked out his long leg and sent the sonic sailing into the stalls! At once, the blanketing silence cut out.

‘I took care of that horrible fat man in the disgusting suit,’ cried Piccolo. ‘He discovered my secret and tried to make me pay. Instead he paid! With his wretched little life! I sang at him. Sang until his silly head exploded! And now the fatal note, which I have laboured years – years – to perfect! The voice of God himself! It will be Mazzini’s undoing too! The undoing of you all!’

He steadied himself, inflated his huge chest and sang as he had never sung before. It was a single, pure note, unbearably sweet but somehow terrible. Rising, rising, rising in pitch like a true siren call. The Doctor howled in pain. Madam curled into a ball, pulling her coat over her head, the sound penetrating even her ancient, natural defences.

Which was when I entered, stage left, my scarf wrapped round my head like Marley’s ghost and brandishing a stirrup-pump fire-extinguisher!

Piccolo turned, still singing, and, in manic haste, I pumped up the instrument as he advanced on me. All at once, a jet of water shot out of the extinguisher into the horn that projected from the mouth of the mask contraption – and Piccolo spluttered and gasped for air.

Grabbing the opportunity, the Doctor reached out and grabbed Piccolo by his shins, knocking him off balance and slamming him to the stage. Then, for some reason, he started fiddling with his own boots!

Piccolo sat up and snarled at the Doctor, his voice distorted by the weird machine. The Doctor was still preoccupied, feverishly undoing his bootlaces.

Piccolo turned the blank sockets of his mask to the Doctor and squealed: ‘And now! Now it is your turn! You think anything can stop me? After all these years!’

He took a huge breath – and the Doctor leapt at him, stuffing one of his socks deep into the brass horn! Piccolo clutched at his mask but the respite from the deadly song was all the chance we needed. Madam unrolled herself, jumped onto Piccolo’s chest and flattened him. I grabbed at the mask-machine – and wrenched it off his head.