In this hugely enjoyable film adaptation of Alan Bennett’s 1999 National Theatre play, The Lady in the Van, Maggie Smith reprises her stage and radio role as the cranky bag lady who parked her decrepit van in Bennett’s Camden driveway in the mid 1970s and didn’t budge from the spot until her death 15 years later.

As imperiously rude as the Dowager Countess of Grantham but considerably less fragrant, Smith’s Miss Shepherd is a glorious comic creation, a pungent mix of dottiness and iron will – ‘I’ve had guidance from the Virgin Mary,’ she reveals when her parking arrangements are questioned, combining the two – but there is pathos beneath the carapace of eccentricity, with glimpses here of a fretful, turbulent past as concert pianist, wartime ambulance driver and nun.

A worthy foil for Smith, Alex Jennings plays two cheek-by-jowl versions of Bennett himself, a bickering double act of Bennett the writer and Bennett the man, one aware of the copy to be mined from his accidental neighbour, the other wary of the mess she leaves behind.

Directed by Nicholas Hytner (Bennett’s past collaborator on those stage-to-screen hits The Madness of King George and The History Boys), The Lady in the Van gains an extra fillip from being filmed in the same street (Gloucester Crescent) and house (Bennett’s own) where the original events took place. Something else to look out for is the presence of The History Boys alumni, including Dominic Cooper, James Corden, Russell Tovey and Samuel Barnett, who pop up in small roles throughout the tale.

Certificate 12A. Runtime 104 mins. Director Nicholas Hytner