Christmas ads: John Lewis, Tesco, Amazon go for tear-jerkers, as others find festive fun

Taken as a whole, advertisers are set to spend a record £10.5bn this festive season, according to the Advertising Association and World Advertising Research Centre.

John Lewis, for its part, doesn’t disclose how much it spends on its Christmas advert, but Ms Lock admitted it was “incredibly important commercially”.

Whether the money pays off is hard to tell, but experts say it’s about more than just getting consumers through the doors.

“Adverts have become part of the ritual surrounding Christmas,” Prof Helen Wheatley, a historian of television, told BBC News.

“The tradition continues, partly because it’s an absolutely prime time for retailers to be speaking to potential consumers,” she said. “And partly because it’s entrenched and it’s something they’ve always done.”

Prof Wheatley pointed out that while we think of them as “Christmas TV adverts”, they are now also huge online moments, with the ads being shared widely on social media.

But she said that some things don’t change – with retailers keen to conjure up a sense of cosiness and familiarity.

“It’s a moment where the nation comes together,” she added.

“We know people get quite excited about the festive adverts. It’s a marker in people’s years and has become part of that Christmas countdown.”