Its predecessor seat, Lewisham West, from which this constituency was largely created, was a marginal bellwether for much of its existence, flipping back and forth between Labour and the Conservatives. The Conservative Party gained it in 1979, the year their Prime Minister Margaret Thatcher came to power and returned her party to government. However, Labour won it back in 1992, despite failing to win the election nationally; it has since become increasingly safe for the party. This is attributed to the area becoming more ethnically diverse and less suburban in character, a trend which has favoured Labour. Despite the 2010 boundary changes adding parts of the Beckenham constituency, which has historically been a safe seat for the Conservatives, these wards are now inclined towards Labour and represented by the party on Bromley Council. Together with the remaining areas in Lewisham, which compose the bulk of the constituency, this means that all wards included in Lewisham West and Penge have a full slate of Labour councillors, and the constituency is thus dominated by the party at both local and national level.