In June 1940 the British government was desperate to get back the treaty ports which they had given to Ireland in 1938. They began negotiations with the Irish government to see what it would take for Ireland to ally itself with Britian and give back the ports. The Irish wanted ideally to remain neutral but they hinted that a British declaration in favour of a united Ireland might change their attitude.
There were three meetings in all and the British became more accepting of Irish desires. In early July Neville Chamberlain wrote to De Valera saying Britian was willing to make a solemn declaration in favor of unity and would also establish a joint body to examine how unity would be established. Ireland could stay neutral only having to give over the treaty ports. Lord Craigavon when he was finally informed sent an outraged telegram to the British government protesting the negotiations with the Irish. In the end however the Irish side did not accept the British offers and the matter lapsed.
Details are in this book. 1940: Myth and Reality: Amazon.co.uk: Clive Ponting: Books