Are you entitled to an Irish passport?

After the Brexit vote in June 2016, so many Britons applied for Irish passports that Ireland's foreign minister had to ask them to stop - pointing out that the UK remains, for now, in the EU. If some of the figures that have been quoted are correct, the Irish passport service may find itself completely inundated in future. But does one in four Britons really have Irish heritage? Tim Harford reveals the dubious history of that number and attempt to estimate the number of Britons who are actually entitled to dual nationality with Ireland.

First broadcast on More or Less, 4 September 2016.