Catherine Tate is a bizarre phenomenon. Her rise over the last few years has been so rapid that the expression “meteoric” seems to have been made for it. She’s now a big enough name that pretty much everyone in Britain has surely heard of her, but for those who haven’t watched her BBC2 comedy sketch series, modestly entitled The Catherine Tate Show, the precise nature of her talents seems a little vague.

After all, Tate’s most famous character, the fast-talking ignorant loudmouth teenager Lauren with her irritatingly awful catchphrase “Am I bovvered?”, seems little more than a rip-off of Little Britain’s Vicky Pollard. The sketch she did with former Prime Minister Tony Blair for Comic Relief earlier this year may have given Tate more exposure, but – remarkably, for such an unpopular politician – it was Blair who stole the show. Likewise her appearance in the 2006 Doctor Who Christmas special was watched by millions more than watch her own show, yet – as always – it was David Tennant’s Doctor who dominated, and many fans of that series are dreading her return as a regular character next year.

But to each their own – Tate evidently has her fans, or her impressive rise to stardom would never have happened. Now, it would seem, it’s time for her to try her hand at the big screen and a bit of slightly more serious acting than she’s been used to to date.

Written by the team behind last year’s fun, low-key British period comedy Sixty Six, on the surface Mrs Ratcliffe’s Revolution could look to be more of the same. Whereas the last film from writers Peter Straughan and Bridget O’Connor revolved around a slightly odd yet almost overly normal family in a depressed suburban Britain in 1966, this one revolves around a similar family from a similar background, only it’s set a year earlier in 1965. To add to the general feeling that the people behind this film know their period, it’s directed by the person who brought us the superb 1960s-set BBC gangster drama The Long Firm a few years back, Billie Eltringham.

So, an up-and-coming British director, two up-and-coming British screenwriters, and starring, in Catherine Tate, one of the hottest British comedians of the moment – at the very least British film fans should take notice, even if its appeal may be more limited elsewhere around the world.

Because where Sixty Six was very much a traditional, light-hearted family comedy/drama, Mrs Ratcliffe’s Revolution, though still a comedy, is both based on a true story and revolves around something decidedly more serious – the 1960s undercurrent of class antagonism, radical politics and the Cold War. Because the Ratcliffe family at the heart of the film end up so taken with Communist politics that they abandon their lower-middle-class lives in the UK to defect to East Germany and an imagined Communist Utopia.

Which all means, of course, that there’s a decided hint of melancholy and frustration underlying all the amusing culture-clash hijinx, and a serious message about the betrayal of the working classes by both East and West bubbling beneath the surface. Which is hardly what you’d expect from a film starring a woman whose main claim to fame is mocking the ignorance of the underclass.