In the tight dark maze of alleys that wind between the Thames and St Paul’s the pleasures of the living are intertwined with those of the distant dead.

Try it for yourself on a late Saturday afternoon. Start by immersing yourself in the eerie darkness of the Temple of Mithras (ancient stones, reconstructed Roman voices calling for strong drink, a pagan pit beneath the guileless Bloomberg building); emerge and cross over to the Roman Watling Street, where you will see tribes of Essex women – Boudicca’s spiritual daughters – with faces of bronze, brandishing not fire but fags and lighters...