Wilton's Music Hall in Graces Alley, E1, is less than a five-minute walk from our London flat. It’s the oldest surviving music hall in the world and has stood in its current form since 1859. There’s also a bar selling cask beer that’s open to the public during performances. We’ve owned our flat for 29 years and, despite always meaning to visit, we never quite got round to it. We hadn’t even walked…