After a number of references to Lyon's Corner Houses in Agatha Christie's novels (Tommy and Tuppence had tea there in one of their first novels), I had to run a Google search on them. I had never seen on in London. Sure enough, they were gigantic teashops run at the turn of the century until sometime after the war. They were the big brothers to the smaller Lyon's Teashops. It became defunct in 1998 (I think). There are even some tariffs from the teashops dating from the 1940's and around 1912. Iced Bovril with soda, anyone?

The prices sure beat this one teashop I saw off Kensington Church Street that sold toast for £3!!!