From the Bulletin of the Society for the Study of Labour History (no.47, Autumn 1983) we have a report of Belfast anarchists being represented at the 1912 Anarchist conference in Leeds. Other than a mention that at least one delegate was present from Belfast, we have no further information about whether a functioning anarchist group was being represented, nor who the delegate was. Any further information will be welcomed. The report here is the one given to the Leeds Jewish Anarchist Group by its delegate.
We do know that there were anarchists in Belfast at that time. John McAra, a Scottish anarchist spoke from the steps of the Custom House in 1908, which saw him arrested, charged with sedition and then jailed for three months. This was considered newsworthy enough to be reported in the Kentucky Irish American newspaper of Saturday, April 4, 1908.
The Belfast anarchist group which formed at this time appears to have died away after the First World War.