Mary Poppins Returns: Emily Blunt is good, but the film is average-alidocious

Within half an hour of the embargo lifting on this presumed Christmas blockbuster, at least eight reviews headlined with "practically perfect in every way" had appeared on the internet (albeit a few with the word "not" attached). Mary Poppins Returns doesn't meet that description.

It’s not a disaster, either. If we’re forced to stick with alliteration, let’s try: astonishingly adequate in every regard. There is a wearying sense of top-class professionals doing a decent, workmanlike job on a project that daren’t stray more than a few cherry tree-lined streets from its familiar origin.

That will probably be enough to keep it in cinemas until the little devils are back in school.

No sequel that bends itself so closely to the original's shape can hope to avoid close comparison. This thing is practically a remake. We are in the 1930s and the two children that Julie Andrews bossed around have grown up into Michael Banks (Ben Whishaw), an unsatisfied widower, and Jane Banks (Emily Mortimer), his politically active sister.

The film’s one endless, repetitive crisis is kicked off when the mean bank – draw your own parallels with our current discontents – calls in a huge loan and threatens to fling the family in the street.

There then develops a lengthy search for a share certificate that will allow Michael and Jane to remain in their enormous mansion. This is not the depression as most citizens experienced it.

Who will save them? Mary Poppins, of course. As all seems dark, the flying nanny, in the fragrant form of Emily Blunt, descends from the heavens and sets to sorting out Michael's three children. Actually, Mary doesn't do that much saving. Taking the search for the certificate as a premise (you're on the edge of your seat, right?) she drags the children into various animated and semi-animated adventures – underwater larks in the bath, Victorian pranks in a magical bowl, a broad-as-a-barn-door number from Meryl Streep – that serve to advance the plot not the slightest jot.

As we tick along, we encounter familiar turns from the 1964 project. Can You Imagine That? leans into A Spoonful of Sugar. The Royal Doulton Music Hall dares to ape Supercalifragilisticexpialidocious. I knew Supercalifragili. Supercalifragili was a friend of mine. You, sir, are no Supercalifragilisticexpialidocious!

Again, it's not that the songs are bad. It's just that – unlike the Sherman brothers' little masterpieces – they are astonishingly adequate in every regard. (Underneath the) Lovely London Sky, a song by Jack the lamplighter (Lin-Manuel Miranda), sounds like what you might get if you asked Siri to sing you an industry-standard London lament. Does even the most devoted Londoner think the skies there "lovely"?

When it was announced that Emily Blunt was to take over from Andrews, the Hosannas from Poppinsians was deafening. She’s good. She can’t sing as cleanly as her predecessor, but she can sing better than any other plausible candidate. Blunt is probably a better actor than Andrews, but the warmth is here buried beneath a few extra layers of well-buffed severity. When this Mary is cross you suspect that she really, really means it. But she’s fine. She’ll do well enough.

Miranda is more of a worry. The creator of Hamilton – and thus a key cultural force of the age – is stranded between "silly" cockney (in the style of predecessor Dick Van Dyke) and something close to how Londoners actually talk. The result is neither and the performance is unexpectedly bland.

In truth, the movie, as anonymously directed as all Rob Marshall’s work, sags on the rare occasions when Blunt is not on screen. The sheer effort she flings at audiences will keep them awake and diverted. The scary charisma is a draw in itself. None of Blunt’s hoofing and hollering can, nonetheless, distract from the lack of anything new going on. There are hints here and there. The implications of a cross-class romance between Jack and Jane – something as inconceivable as interspecies romance in PL Travers’s source books – never gets any further than glances and whispers. The introduction of a few people of colour in minor roles feels like window-dressing.

Averagealidocious. See me after sums.

Opens December 21st