I think the political and economic crisis of the 1970s did throw up an ideological divide. Thatcher won.
Callaghan resigned early to ensure his successor would be elected by Labour MPs alone and not by an electoral college. The right-wing majority in the PLP elected Foot. He had one function: to contain the left until the right could reconsolidate their power in the party. He fulfilled his role perfectly.
Foot was from the British establishment and was a dissident within it. He never gave up his support for either – the establishment, nor being a dissident.