There are two hypotheses as to the relationship between her period in Opposition (1975-79) and her time in Goverment (1979-1990). One is that one led to the other – in essence, a Whig view of history – with Thatcherism being developed in readiness for office and a solid base of electoral support established in order to usher in a lengthy period of Government. The other is that the two are essentially discrete periods, with Thatcherism and a solid base of support being the product of her premiership and not the other way round.
The second hypothesis the most persuasive. We tend to view Margaret Thatcher through the prism of her time in office. She was a formidable, certainly a distinctive, Prime Minister. However, as a Leader of the Opposition she was anything but formidable. She was not particularly successful. She was poor at public communication. She performed poorly in the Commons and tended over time to stay away. She was not good on television. She was constrained in imposing her views on the party. She inherited a non-Thatcherite Shadow Cabinet and was not able to mould it to her wishes. Her personality was seen as combative and dogmatic. Though Labour became massively unpopular mid-Parliament, it clawed back support and by mid-1978 some polls showed a Labour lead. Perhaps more tellingly, at the personal level, Labour Prime Minister James Callaghan enjoyed a twenty-point lead over Thatcher.
The Conservatives won in 1979 because of the ‘Winter of Discontent’. Labour support plummeted in the wake of union action. Margaret Thatcher’s form of leadership appeared – for the first time – more attractive than Callaghan’s consensual approach. As a result, Margaret Thatcher entered Downing Street. Once in office, her eponymous philosophy emerged, though being first identified as a coherent philosophy by opponents (some essays in Marxism Today). The PM also emerged as a powerful leader and conveyed a sense of direction. The success of the Conservative Party in the 1980s was not the result of Thatcherism – the PM was able to craft neither a Thatcherite electorate nor even a Thatcherite parliamentary party – but the result of Margaret Thatcher, able to convey to the electorate that she knew where she was going.
The ‘Thatcher legacy’ derives from her period in office. Had James Callaghan called an election in 1978, there is a good chance Labour would have won. Had that happened, then Margaret Thatcher may have been ousted from the leadership and passed into history as a not particularly successful leader. Margaret Thatcher became leader of the Conservative Party because of the failings of Edward Heath. She became Prime Minister because of the misjudgment of James Callaghan.