It sounds like some in the Irish parliament were getting restless.
In the Eire Chamber of Deputies to-day, the Minister for Supplies will be asked when he will permit the resumption of supplies of stout and beer to Northern Ireland and Great Britain.
Belfast News-Letter - Tuesday 23 November 1943, page 3.
It wasn’t just Northern Ireland that was having to do without Guinness. Although Guinness had a brewery in London, it didn’t supply the whole of the mainland UK. The north of England and Scotland got their Guinness from Dublin. It was still like that in the 1970s and 1980s.
The reply of the Irish Minister for Supplies reveals what this was all really about:
“Irish Stout and Beer: Mr. Lemass, Minister for Supplies, said in the Dail yesterday that the export of stout and ale to Great Britain and Northern Ireland will be resumed as soon as the cereal position permits.”
Birmingham Daily Post - Wednesday 24 November 1943, page 4.
Namely, the Irish government wanted more grain from the UK and were using Guinness as a bargaining chip. As soon as the UK government gave in, Guinness began to flow across the border once again. Supplies had been interrupted for about a month.
Supplies for Ulster Next Week
THE ban on the export of beer and stout from Eire to Northern Ireland is to be lifted from Monday next by the renewal of the export licence. The embargo was enforced a month ago.
Messrs. Guinness have intimated that the quota to publicans will be increased from 60 to 75 per cent. of the basic supply for the period, July to September, 1941.
While porter may sold in most public-houses in Belfast on Monday or Tuesday, it is expected that bottled stout will not be available until the end of the week.
The suspension of supplies last month meant the dismissal of about 300 barmen in Northern Ireland.
The Eire Minister of Agriculture stated in Dublin last night that the export of beer and stout was to be resumed under licence, since it had been found possible to arrange for the importation of barley.”
Belfast News-Letter - Thursday 02 December 1943, page 3.
You can see that publicans couldn’t get as much Guinness as they wanted, but were rationed to a proportion of what they had bought in 1941. Those 300 barmen must have been happy to get their jobs back.