Its tear-jerker adverts signal the start of Christmas in many households.

But this year’s festive offering from John Lewis featuring Moz the Monster has sparked a very mixed reaction from viewers.

According to a child development expert though, the department store has got its 2017 big budget commercial just right.

And that’s because as many as half of all children have an imaginary friend.

John Lewis' Moz the Monster Christmas ad

This year’s ad cost £7m and was filmed by an Oscar-winning director.

It features a small boy and his enormous imaginary friend named Moz, who helps banish his night-time fears.

It has earned the approval of Dr Paige Davis, a psychology lecturer at the University of Huddersfield.

She’s also one of the world’s leading academic researchers into the widespread phenomenon of the imaginary companion (IC) or the “personified object” – when imaginary life is breathed into a toy such as a teddy bear.

University of Huddersfield child development expert Dr Paige Davis on Moz the Monster John Lewis ad

Dr Davis, a developmental psychologist, was quick to see the commercial when it made its debut, watching it through expert eyes.

And her verdict of the two-and-a-half minute film is that “it’s really accurate.”

She explained: “I like the fact that the makers don’t stick to the antiquated idea that ICs are bad.

“Children use ICs functionally for many different purposes and in this case it is to alleviate fear of the dark.

“The commercial is very accurate on how kids see their imaginary companions. This child really plays with the IC and has strong feelings for it.”

American-born Dr Davis – whose general interest in child development led to her speciality in ICs – relocated to the UK for doctoral study and her lecturing career.

She has now written a sequence of academic articles on the subject of imaginary companions.

Her work has triggered widespread interest, having been featured in some high-profile US TV shows.

John Lewis Christmas advert 2017 - Joe with his gift from Moz

She is now working with her university colleagues Dr John Synnott, Dr Maria Ioannou, and Kalliopi Tzani-Pepelasis.

They have formed The Imagination Consortium, which will take IC research a stage further.

The consortium has formed a collaboration with a primary school in Yorkshire, where its members will work with approximately 30 children on the topic of imaginary friends.

They will carry out simple tests designed to appraise whether or not social and educational skills have improved as a result of having an IC.

Dr Davis said at one time the standard response of teachers and parents was to worry about children who created fantasy friends.

However, new theories developed in the 1990s argued that ICs could improve the mental, social, and verbal skills of young children.

Dr Davis has been building on this research and her new projects will help her investigate what she describes as “the direction of causality” – whether or not the children who create imaginary companion are doing so because they have better mental skills.

She said: “The research aims to dispel the myth of the IC as being problematic and instead position Moz where he should be.

“(This is) as a supportive tool that a child can use to stop being lonely, talk through a problem with, or conquer a fear of the dark, which the John Lewis advert shows well.”