The Charing Cross, Euston and Hampstead Railway was opened on 22 June 1907; and was known as the Hampstead tube. It linked the northern suburbs to central London through deep tunnels under Hampstead Heath. By 1926, an extension opened to Kennington meeting the City and South London Railway.
By 1927, the experience gained in the technology needed to build deep tunnels allowed the company to propose an audacious plan to link Hampstead to the Place Vendôme in Paris. The plan met strong resistance from Winston Churchill — who was concerned at the danger from continental Europe, but was supported by politicians seeking to get Britain back to work after the Great Depression. The Bill gained Royal Assent in 1929; and began to raise finance. Tunnels were extended to Morden, on the outskirts of South London; but the markets failed to purchase the complex financial instruments needed to fund the construction. This ended the hopes of the company; and the crisis caused the company to be taken into public ownership on 1 July 1933, by the London Transport Board.