Every now and then, a bit of ancient London inserts itself into our consciousness. A view of Londinium at Riverside wall in the Tower of London, the 12th-century St Bartholemew-the-Great, that kind of thing. But there’s an alternative one too, and it’s brilliantly evoked by a new series on BBC4, ‘Dreaming the Impossible: Unbuilt Britain’. In it, architectural historian and investigator Dr Olivia Horsfall Turner looks at projects that never saw the light of day, kicking off with a vast glass arcade by the great Joseph Paxton that would have given London an 11-mile transport system across the city. Why wasn’t it built? Watch this utterly absorbing new series to find out. Yolanda Zappaterra
Read our review of ‘Dreaming the Impossible: Unbuilt Britain’, airing on Mon Aug 12, 9pm, BBC4.