The Irish border

Sir: Contrary to the assertion that the Irish border ‘only hit the headlines’ after Leo Varadkar became Taoiseach in June 2017, as Liam Halligan claims (‘Irish troubles’, 24 November), the negative impact of Brexit on the peace process and the Good Friday Agreement was clearly signalled during the referendum campaign itself, including by the Irish government and by two former British prime ministers, Sir John Major and Tony Blair.