For me, last night provided the defining moment of the campaign. I was in the audience of 6,000 or so at the Wembley Arena listening to the final major debate, hosted by David Dimbleby.

As far as I could tell, the evening was turning into a win on points for Vote Leave. Ruth Davidson, for the Remainers, had some moments of real success. She banged out a long list of military people who maintained that Britain would be safer within the European Union. She said she was going to take the words of these experts seriously even if the Leave speakers did not. But Andrea Leadsom, for the Leave side, was good and to the point. She was also smiley and sunny in a way that none of those speaking for the Remain side were.

Sadiq Khan had obviously been told not to jab his finger at people when trying to make them agree with him but he was struggling to abide by the rule, jabbing a slightly curled finger at us instead. He called people liars and looked angry and sour. He still got applause though. The audience was split 50:50 between Leavers and Remainers.

The person who was doing best of all was not even on the stage: Tony Parsons. He was one of the commentators at the other end of the hall who had a knack of bashing the Remain arguments on the head in a modest down-to-earth sort of way.

Meanwhile, Boris sounded as though he was winging it. He talked as if he were making it up as he went along, relying on his cleverness to get through the night. It made him appealing but not terribly effective.

Overall, though, the Remain side was angry and scornful. Not a good look. Then came the summing up. First came Ruth Davidson. She did a punchy, workmanlike effort and got warm applause from the Remainers in the audience. But it still seemed a game of point scoring.

Then Boris strode towards the lectern at the front of the stage with an unusual look of determination. He remarked how the other side in this campaign had talked of 'nothing but fear of the consequences of leaving the EU' whereas his side had offered hope. He talked of 'those of us who believe in Britain'. The other side said 'we have no choice but to bow down to Brussels.' Lowering his voice, he returned, 'We say they are woefully underestimating this country and what it can do.' He pointed out the powers and the money we can take back and said we can speak up for 'the democracy that is the foundation of our prosperity'. He added that 'if we stand up for democracy, we will be speaking up for hundreds of millions or people around Europe who agree with us but who currently have no voice.' Suddenly voting leave became about democracy, self-belief and those who were denied a voice. The idea of leave became aspirational and even heroic. Making his hand into a fist of resolution, he declared that if we vote leave tomorrow and take back control, 'I believe that this Thursday can be our country's independence day!'

This short speech marked a complete change of atmosphere. That is why it was so potent. It was hopeful, ambitious. The Leave side of the audience was thrilled. For the first time in the evening, people spontaneously started standing up as they clapped. The BBC coverage which I saw later showed just a few people standing, but I can tell you more and more people stood up all around the hall and up at the sides. It was an extraordinary moment because finally we were released from the self-doubt, niggling fears and negative claims. It was a moment of 'Omigod! Of course we can do this!'

At last Boris came good. It was one of the best moments in politics I have ever witnessed. Unfortunately it appears that journalists in the 'spin room' missed it as the sound had been turned off. It should have been on the front page of every newspaper and led every television news report. Do watch it above. This was his finest hour. Well, minute, anyway.