Yet another 'lost' street has been in the news recently. This time it's in Stockton-on-Tees, County Durham, beneath a Georgian town house in the centre of Stockton known as Gloucester House, currently being refurbished. See here and here. The 'street' appears to be a series of storerooms and possibly accommodation for servants (although I think they are probably more storage areas), linked by passages. Talk in the articles of the 'secret tunnels' linking to other parts of Stockton is characteristic of all such discoveries and reports, but is extremely unlikely.
Author of Subterranean City, Beneath the Streets of London, London's Coffee Houses, Decadent London, The Folklore of London, Subterranean City (Revised and Expanded Edition), Netherwood, Last Resort of Aleister Crowley, Lord of Strange Deaths, the Fiendish World of Sax Rohmer; Secret Tunnels in England, Folklore and Fact