Bulgaria–United States relations to work. Bulgaria became a member of the Warsaw Pact on May 14, 1955. Though no Soviet troops were stationed on Bulgarian soil, in 1968, Zhivkov sent a Bulgarian division to join Polish, Hungarian and Soviet troops to crush a popular uprising in Prague. In 1978, the Bulgarian secret police were implicated in the assassination in London of Georgi Markov, a Bulgarian dissident who was a correspondent for the BBC World Service, Deutsche Welle radio and the U.S. sponsored Radio Free Europe. Markov was assassinated with a poisoned umbrella on September 7, Zhivkov's birthday. The rise of democratic movements across
London Buses route 7 from Wormwood Scrubs were renumbered 7A. This situation remained until 3 October 1934, when the newly constituted London Passenger Transport Board instituted its own numbering system. Route 7 continued with an extension to Kew Green until 22 August 1946, when the 7A was revived from Acton to London Bridge. Route 7 was withdrawn on 19 August 1958. From 14 October 1959, the old route 7A had its suffix removed, becoming plain 7. The service ran between Acton tram depot and London Bridge station via East Acton, Ladbroke Grove, Paddington station, Edgware Road, Marble Arch, Oxford Street, Holborn station and Bank