Thanks for all the London tips. There are some brilliant things in there including the location of Sunshine Desserts from Reggie Perrin. Not sure if this is one of those things that everyone knew except me, but 1960s curio The London Nobody Knows is on YouTube. Part one is above and here are parts two and three. I only found this after I'd bought the DVD although all is not lost as it's (a) better quality and (b) paired with charming piece of 1960s whimsy Les Bicyclettes de Belsize (opening credits).