Start at the Tower of London, and walk to Cable Street. Turn into Grace's Alley, a narrow path with a set of terrace houses on one side and a high wall on the other. Surely the music hall isn't down here?
But, as they say in pantomime, "Oh, yes it is."
Halfway down the terrace there's a door, slightly larger than the rest, and behind this is a warren of bare rooms. In one of these Broomhill Operas, which now runs the premises, has set up home and Steve Higgins, music education officer, and Netia Davon-Whetton, an opera director, are waiting for the arrival of a group of 30 eight to nine-year-olds.
When the class, from Halley primary school, Stepney, arrives for its two-hour workshop they are full of anticipation but unsure what to expect.
They first hear the tale of one John Wilton. In the 1840s Mr Wilton ran a highly successful pub which was popular with singers but he always hankered after a music hall of his own. To this end, he bought first one house then another in Grace's Alley until he owned a long row, then he knocked through the walls to create his dream theatre. Wilton's Music Hall eventually opened to the public on March 29, 1858.
After the talk the children squeeze through a narrow doorway into a theatrical treasure: a long, dusty room with a high, but shallow, stage and a proscenium arch. On three sides there is a narrow balcony, supported by slender gold-painted columns decorated with a barley motif. In its heyday up to 1,500 people would cram in here for every kind of act - from lady acrobats to comedians, from jugglers to sopranos.
What makes the survival of Wilton's so astonishing is that it actually operated as a music hall for less than 30 years. By the 1880s it had closed after John Wilton retired and licensing laws proved an obstacle to the somewhat bawdy content of its shows. With an abrupt change of identity, the building then became a Methodist mission hall and soup kitchen, then finally a rag warehouse.
"What do people do at a music hall," asks Steve, sitting at the piano. "Sing", chorus the children obligingly, as they sit below the stage. In no time at all "Daisy, Daisy..." and "Sweet Molly Malone" are ringing through the rafters with gusto. There is audible concern when Molly pops her clogs, but the children recover sufficiently to finish with an ear-splitting chorus.
Then it is Netia's turn to tell a story with Steve adding incidental music on the piano. It's about a girl called Lizzie, a child flower- seller who saves up her pennies and hides them under the floorboards until she has enough to go to, yes, you've guessed it, Wilton's music hall. "What does she find there," asks Netia, "but a warm, bright, loud, joyful atmosphere." And with that they are straight into a chorus of "Maybe it's because I'm a Londoner".
Afterwards, the children go up to the gallery to admire the view enjoyed by the rich people who came to Wilton's. From here, it becomes obvious why the stage is as high as it is: any lower and the sea of top hats would have blocked the view.
The children go on stage, where they are taught to look at the audience, click their head to the side and bow deeply. Curtseys are practised and kisses blown.
Back in their seats, Steve plays happy, then funny, then sad music and the audience has to find words to describe it. They aren't sad for long as they burst into "There was I, waiting at the church..." and then get really excited when they spy the costumes hanging up invitingly by the stage. They are going to have the chance to perform on stage themselves. Netia rehearses a show in which everyone has a part: from joke-telling to knock-about slapstick routines.
The children separate into two groups - one writing songs with Steve, the other working on poems with Netia. Steve asks them to expand on his first line: "There was a big beast..."
After that comes the performance. This includes a memorable comp re in a top hat which almost covers his eyes, and a comedy routine which goes: Q "How did the cow get to Birmingham?" A "On the motorway." Boom, boom.
Wilton's is still semi-derelict, but thanks to donations of materials and tools from Jewson's it is now safe. It's an inspiring place, as both children and performers must have felt after a workshop which mixed fun and education in perfect proportions.
Wilton's Music Hall, Cable Street, London E1. For details about visits and workshops contact Flora Smith, Broomhill Opera. Tel: 0171 702 9555. email@example.com