Like Margaret Thatcher, Jeremy Corbyn is not a natural comedian. That’s okay – if being a standup was a prerequisite for being Prime Minister, then the Iron Lady would have rusted in obscurity.

But it does make it a dubious decision to open his speech with a barrage of scripted jokes. Doing so suggests that Team Corbyn aren’t yet really sure of who their man is, or how they are seeking to present him. I suspect he is far more successful in his natural environment – such as the Times picture today of him resplendent in socks and sandals – than when they try to make him someone he isn’t.

It was a wiser decision to follow the jokes with some pleasant thanks – to the family of the speaker who introduced him, to the Islington North CLP and to his competitors. Just as at his first PMQs, he’s at his best when he isn’t very interesting.

It’s when the new Labour leader tries to strike a blow that he gets bogged down. He’s undoubtedly right about the abuses of the Saudi tyranny, but picking it out as his first political point raises yet again the question of why he has in the past described Hamas and Hezbollah – no more lovely, democratic or tolerant of democracy than the Saudis – as “friends”.

After that initial prod at David Cameron, it was onto safer topics. He was guaranteed applause on “Tory cuts”, house prices and the uncertainties of the labour market. The speech came to sound like the standard pitches delivered by any Labour conference delegate, rather than a rallying cry from a would-be leader of the nation. Some politicians may campaign in poetry, but Corbyn stuck firmly to the beige prose which has served him for the last thirty years.

It’s increasingly clear that Corbyn’s biggest problem is his history. In part he’s harmed by his history of dubious comments and even more dubious alliances, but more fundamentally he’s hobbled by the political environment in which he has spent his adult life.

The hard left has a deserved reputation for endless speeches, endless jargon and endless platitudes. Corbyn once praised a Chavez speech which lasted for five hours, so attendees in Brighton got off lightly today. But he seems incapable of shaking off a rhetorical style and message which is better suited to a rain-swept protest of a dozen converted radicals than a pitch for the nation’s swing voters.

That approach might get him by if his name was known, his platform wildly popular and his position secure. But he faces the poorest starting approval rating of any Labour leader, and there are plenty in his party – pragmatists, not just zealous Blairites – who already despair of his leadership.

What’s more, either the team around him aren’t giving very good advice, or their leader simply isn’t listening to them. As John McTernan, a veteran Labour apparatchik, said yesterday it seems the new politics is just like the old politics, just not done as well.

The future still looks rocky for the triumphant left. Corbyn was elected on his declared principles, and has since that election had to fight over them each day with his own Shadow Cabinet and Parliamentary Party. Today he chose to shoot back against Trident, despite the unions’ warnings and reports that yesterday the Labour conference (perhaps unawares) voted in support of Trident renewal.

That decision was, as Sir Humphrey might say, courageous – had it come within a speech which established his genius and his dominance then he would have got away with it. Instead, it came within a not very interesting ramble which suffered from at least one false finish – and as such it simply guarantees another bout of fighting with his internal critics.

It is his power in the grassroots which keeps him safe from rebellion – so far. MPs are afraid of deselection by the Corbynites. But that won’t last forever, either the left will get bored at the realities of leadership or the MPs will find their fear of the voters comes to outweigh their fear of their own party members. Therefore, he has a limited amount of time to impose his authority on his party at the top, before the chance dissipates. There is still little sign of him starting to do so.

Today’s speech didn’t make things better, nor did it make them very much worse. It was simply Corbynish – but unfortunately for him that isn’t going to become a compliment any time soon.