Why does talk of a Labour landslide worry Keir Starmer?

On Saturday evening, Sir Keir Starmer addressed hundreds of Labour activists in a large hall in central London. The Labour leader knows the opinion poll shows power is within his grasp. Forecasts suggest he could even make history with the largest ever Labour majority in parliament – winning by even more than Tony Blair achieved with his 1997 landslide.

Yet the event had an air of deliberate caution, tempered by fears of comparisons with 1992 and that the feeling a Labour government is already guaranteed will see the party leak votes to the Lib Dems and the Greens.

Sir Keir and his deputy Angela Rayner spoke to around 400 activists at an invite-only meeting at the Royal Horticultural Halls, a short walk from 10 Downing Street, the house he is on course to make his home on Thursday.

But he warned Labour activists the “hardest mile” was still ahead and asked them to imagine waking up to another five years of Tory government. That “could happen”, he said, because polls suggest millions of people have yet to decide how they will vote.

Despite the modest and understated air of the event, the excitement in the room was clear. When London mayor Sadiq Khan arrived about 10 minutes before kick-off, the tension that had been building up in the room could be contained no more. A huge round of applause burst out. It took him almost a full five minutes to take his seat because of the number of people queuing up to shake his hand.

Similarly, Rachel Reeves was greeted like a pop star. Young women lined up to meet and talk to the politician set to overturn 800 years of history and become the UK’s first female chancellor.

During the event, the party unveiled a headline-making endorsement from showbiz legend Sir Elton John. But he was far from the only one. The party also secured the backing of the actor Kit Harington, who plays Jon Snow in Game of Thrones. And James Norton. And a dragon from Dragons’ Den. And on and on it went.

But even these big names were wheeled out in what seemed a deliberately modest way. Most appeared on video, although comedian Bill Bailey was in the hall. And even the screens, a couple of which were dotted around the room, were smaller than you might expect. More small screen than “big screen”, the kind of thing you might expect to see in a primary school hall.

For a couple of reasons. Sir Keir is serious about his message that he wants to end politics as soap opera and bring back the return of grown-up government.

But he also wants no comparisons with the infamous Sheffield rally in 1992. Then, at a similar stage in the campaign, Neil Kinnock told around 10,000 in Sheffield Arena: “We’re all right!” The event has gone down in history as one where a party’s optimism about the result allowed it to get carried away.

But there are also fears the belief Labour are a shoo-in will lose them votes.

At the rally, Sir Keir pleaded with voters to give him a “clear mandate” to govern, large enough to implement his agenda.

Senior party figures worry many people who might be included to vote for them will not come polling day – precisely because they think a Labour government is already guaranteed.

Under those circumstances, smaller parties like the Lib Dems and Greens could pick up more votes. This could help those parties to win some seats – or allow some Tory candidates to come up the outside lane.

Either way, expect to hear plenty of Labour figures saying election victory is by no means in the bag over the next few days.