What is Britain deciding?

A referendum on June 23 will ask voters whether the country should “remain a member of the European Union” or “leave the European Union.”

Who is voting?

British citizens over 18 (although not all of those living abroad are eligible), and residents of Britain who are citizens of Ireland or of the Commonwealth, which includes 53 countries.

Is this vote final?

Yes — at least for the foreseeable future. If “leave” wins, there will be a two-year negotiation with the European Union about the terms. It is unlikely to be amicable.

Has this happened before?

Britain joined the European Economic Community, the predecessor of the European Union, in 1973. In a 1975 referendum, more than 67 per cent voted to remain.

What is likely to happen?

Broadly speaking, opinion polls show the population divided evenly. Market analysts and betting shops think that voters will choose to remain.