Theresa May was said to be incapable of spontaneity. Her performances were dismissed as wooden and undramatic.

Those criticisms no longer apply. Today’s speech was one of the most dramatic in the entire history of party conferences.

By the middle of this perfomance, we seemed to be living through a grand opera rather than a party leader’s address.

It seemed possible the Prime Minister was going to die on stage. Her voice certainly was dying. It went, came back, faded, returned, weakened, was revived by a cough lozenge supplied by the Chancellor of the Exchequer, seemed finally to be going.

The conference willed her to carry on, and she willed herself to so, though there were times when it looked touch and go. Through repeated standing ovations, prolonged outbursts of spontaneous emotion and loyalty, the Tory tribe sought to supply her with the time she needed to recover.

“They love her more now. They were shouting ‘Come on Prime Minister’,” a journalist who was sitting surrounded by Conservative delegates reported.

They were very angry that in the first sign of things going wrong, she was interrupted by a prankster waving a P45. She had just begun seventh page of a densely typed 15-page speech, and although she had started strongly, the atmosphere was growing ever so slightly somnolent.

Not once the prankster had struck. Photographers stampeded towards him from every direction. The conference expressed its indignation, and its support for the Prime Minister, as he was ejected from the hall.

When she was able to resume, the Prime Minister came back by declaring: “I was about to talk about someone I’d like to give a P45 to – Jeremy Corbyn.”

But she looked shaken as well as angry, and had a embattled air as she expressed her faith in the Cabinet, “a team that is determined we will always do our duty by our country.”

On the next page, the eighth, her voice started to go. Like the heroine in an opera, she looked as if she was going to perish on stage.

But first she had very long aria to get through: seven pages of aria. She coughed, spluttered, was brought to a halt. This was agonising. Pity is not an emotion any leader wishes to evoke, but it was impossible to avoid feeling sorry for her.

Would she have to give up? Conference rose to give her the time to collect herself. The applause was prolonged, after which she stopped and starting, struggling to get into any sort of rhythm. The theme running through the speech was “the British dream”, but for her this was becoming the British nightmare.

“Excuse me,” she said at one point, with compulsive politeness. The Chancellor supplied his lozenge, and she joked in the rueful manner of someone with severe flu who is feeling dreadful: “I hope you realise that Conference, the Chancellor giving something away free.”

In her next paragraph, she died again after observing that “private enterprise is crucial”. And in the paragraph after that, where she said “we will adopt a balanced approach to the economy”, her voice trembled so much her ability to continue seemed more doubtful than ever.

The Conference conferred another standing ovation on her, to give her a breather. On she went, talking about “keeping the British Dream alive”.

She was alive, but how vulnerable she looked. Leaders live by words. Silence will not do.

May reached her major announcement, about housing, prefaced by the confession: “It has always been a great sadness for me and Philip that we were never blessed with children.”

But she wants other people’s children to be able to buy homes, “so I will dedicate my premiership to fixing this problem – to restoring hope”.

The Conference gave her another standing ovation. She pressed on, delivering some good lines: “There is a big problem in our politics when a leading journalist from our national broadcaster has to hire bodyguards just to do her job.”

But in a passage about “the cowardly attack on the Manchester Arena” her voice sank to a whisper, fading like a radio whose batteries have expired.

Somehow she revived herself and got through to the end, and there was Philip May on stage, giving her the most heartfelt hug, expressive of deep relief, and beaming for at the Conference with his thumb up.

When did we last see a Prime Minister look so vulnerable? There was no doubt the Conference wanted her to get through this ordeal, and get through it she did, which was a kind of triumph.

The text of the speech was good, the delivery was electrifying, and the party’s affectionate support could not have been more staunch. But even her warmest admirers will want her doctors to testify that she is fit enough to carry on without wrecking her health.