It’s the most wonderful time of the year…certainly for those of us who love nothing better than a good election manifesto before bedtime.

Last night I waded through Labour’s and two things struck me. The first was how attractive some of the policy commitments are. Indeed, the document contains a sack full of early Christmas presents for anyone craving an end to the Tory austerity of the last decade.

There’s significant and much-needed investment for the creaking NHS, of course (which would have a knock-on effect on Scottish health funding). We also see promises to end the disastrous Universal Credit system, take the railways back into public ownership, introduce a £10 an-hour living wage, tax the rich a bit more and give workers more of a say on boards. The focus on young voters in England and Wales is clear and welcome. Commitments to end crippling university tuition fees and make councils build 100,000 homes a year are eye-catching, while an aim to be carbon neutral by 2030 will be applauded by many.

Taken on its own merits, the Labour manifesto encourages conversations around the role the state could and should take. And that’s a good thing. More of us than ever before feel the system is “rigged” against us. It should also be noted that Labour’s planned investment in public services – criticised by some as unrealistic – still wouldn’t match that of many of our European neighbours.

But all this brings me to the other significant thing that struck me while reading the manifesto: how unfortunate it is that Jeremy Corbyn is the Labour leader fronting it.

Don’t get me wrong, the Tories under Boris Johnson sound absurdly hypocritical when they try to tell us Labour’s policies will trash the economy, that the Conservatives are the true party of business and the economy. Indeed, the Brexit debacle has turned the party into a dangerous right-wing faction happy to ignore the pleas of businesses big and small not to leave the single market or end free movement.

But that brings us to the elephant in the room for Labour, the reason its manifesto crumbles before our eyes. Mr Corbyn’s failure to oppose a Tory Brexit from the start means there is every chance Mr Johnson will win a majority when voters go to the polls on December 12. Indeed, the Labour leader will have enabled it. Could he have prevented this? Of course he could.

For a start, Mr Corbyn could have instructed his MPs to vote against the bill to trigger Article 50 – as the SNP did – back in 2017. Starting negotiations with the EU when no one had even begun to formulate a credible way forward has proved disastrous and divisive. How Mr Corbyn could have thought triggering Article 50 would do anything other than hand the Tories the mandate for a Hard Brexit is remarkable. It also highlights how poor his judgement is, especially since it led to the moment last month when 19 Labour MPs voted for the Prime Minister’s deal, thus allowing Mr Johnson to crow that he has cross-party support for “getting Brexit done”.

Then there was the awful decision to sit on the fence over Brexit rather than back Remain. Agreeing to leave the single market and end free movement was breathtakingly bad, too. Who, for example, is going to build all those houses in the manifesto when there aren’t enough construction workers? Opposing Brexit would have given Remain voters in England a clear position to coalesce around. Yes, many of Labour’s supporters voted Leave, but since most don’t back a soft Brexit, he was always at risk of losing them to the Tories or the Brexit party. Instead, the Remain vote is split, which might hand Mr Johnson the majority he needs to forge ahead with a Hard Brexit.

It’s also significant that Mr Corbyn has done nothing to win back support in Scotland. Instead of trying to make amends with the Scots that have deserted his party in their droves, his embarrassingly tin-eared approach to all things Scottish – not least the patronising “a Labour government will see off independence” line – means he stands to lose even his party’s remaining seven seats.

Now, we all know that polls should be treated with caution. But Mr Corbyn has yet to experience the sort of breakthrough moment he did in 2017, when Theresa May’s balloon popped. And it just doesn’t feel like such a moment is on the cards this time around.

Mr Corbyn will have no one to blame but himself if the current polls, which put Mr Johnson way ahead, turn out to be accurate. It’s entirely possible that his stubbornness and poor judgement will prove catastrophic for the most vulnerable in our society, the very people he claims to represent. Unforgiveable doesn’t even cover it.