Britain goes to the polls tonight (Australian time) for its second referendum on membership of the European Union (formerly the EEC). The first one, in 1975, recorded a comfortable 67.2% vote to stay; the one certainty tonight is that, this time, it will be much closer.

Back in 1975, most of the opposition to Europe came from the left. The Conservatives (then in opposition) supported continued membership, while the Labour Party was divided -- most ministers supported a "yes" vote, but the majority of Labour's conference was opposed. The strongest votes to leave came from safe Labour areas, and particularly from Scotland. The strong Tory areas of south-eastern England voted overwhelmingly to stay.