Based on the Wikipedia page .
One of the extensions of the Metropolitan Railway, from Baker Street Station to Swiss Cottage Station in April 1868. There were intermediate stations at St John's Wood Road Station and Marlborough Road Station, both with passing loops and the line was worked by the Met with a service every twenty minutes. A junction was built with the Inner Circle at Baker Street, but there were no through trains after 1869.
See also Bakerloo Line.