The late John Sullivan’s prequel to Only Fools and Horses staggers on to 1962 with Del and Rodney’s mum, Joan (Kellie Bright managing to be both sassy and naive), holding down two jobs to keep the Trotter family going. Meanwhile, Rodney’s biological dad and smooth criminal Freddie Robdal (Nicholas Lyndhurst) is being hounded by DI Thomas (Mel Smith at his jowly best) for the Margate jewellery heist, and young Del (James Buckley) has got engaged to a posh bird called Barbara.Samantha Spiro and Alex MacQueen give wonderfully over-the-top, cartoon-like performances as the up-market Birds. The disdainful yet bewildered expression on their faces when they hear that Del’s dad is a docker is akin to that of Downton Abbey’s Maggie Smith when she enquired exactly what a weekend is.But, despite these moments, most of this is clunky and charmless. And lovely Lambrettas and Golden Egg restaurant aside, some of the period detail is strangely unconvincing. Yet audiences have loved earlier outings. An enduring nostalgia for the Trotters maybe.