In the United Kingdom
In the late 19th century/early 20th century, the Progressive Party was formed as a party that contested local government elections. Members included those who stood at parliamentary elections as either Liberal or Labour party candidates.
At a national level, the relationship that existed between the Liberal and Labour parties from 1906 to 1918 was referred to as the Progressive Alliance.
In the mid 1930s, prominent Labour politician Sir Stafford Cripps advocated a Popular Front where the Labour and Liberal parties would unite with other groups on the left to counter the Conservative dominated National Government. The idea was for the parties of the left to agree to support only one candidate at constituency level. In most cases this would either be a known member of the Labour or Liberal parties but sometimes it would be a candidate of neither party, who would be supported by both parties as an Independent Progressive.
At the 1935 General Election, just one candidate stood as an Independent Progressive, and that was Gerald Bailey at Aldershot. Bailey, a Quaker, had stood as a Liberal in 1929 and since 1930 had run the National Peace Council.
During the 1935-45 parliament, a number of candidates stood in by-elections as Independent Progressives; Thomas Edmund Harvey a former Liberal MP won the Combined English Universities by-election, 1937 gaining a seat from the Conservatives. Sir Peter Chalmers Mitchell fought the Combined Scottish Universities by-election, 1938. Sandy Lindsay fought the Oxford by-election, 1938. Vernon Bartlett won the Bridgwater by-election, 1938, gaining the seat from the Conservatives. Dr Billy Carritt, a member of the Communist party, fought the Westminster Abbey by-election, 1939. Prof. John Alfred Ryle fought the Cambridge University by-election, 1940. Reg Hipwell fought a number of by-elections, the Hampstead by-election, 1941, Scarborough & Whitby by-election, 1941, Salisbury by-election, 1942 and the The Hartlepools by-election, 1943. Gerald Kidd fought the Chichester by-election, 1942. William Douglas-Home fought the Windsor by-election, 1942 and the Glasgow Cathcart by-election, 1942. Alan Dawrant fought the Newark by-election, 1943.
At the 1945 General Election there were only four candidates who used the label; Vernon Bartlett was re-elected at Bridgwater. Sydney Muller Parkman fought Hastings, J. B. Priestley fought Cambridge University and Mary Stocks fought London University. 
- British parliamentary election results, 1918-1949 (Craig)
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