A good question. Not only is it not available in English it's probably out of print in Irish as well by now. As an author Mac Annaidh prefers to work on new books rather than to go back over old ones. His latest (sixth) novel Ar ais go Keriolet was published earlier this year. It's partly set in Brittany in the chateau which was once owned by Prince Youssoupoff, assassin of Rasputin. Literature in Irish has come a long way since M'asal Beag Dubh. Mac Annaidh's first novel was published in Russian translation, none of the others have been translated. This answer from the author himself who can be found on Facebook.