According to the report, he then moved on to Glasgow, where he was in trouble with the police, and in 1931 arrived in Dublin, where he took the new name of Brian O'Neill and worked as a journalist and as a paid activist and pamphleteer of the Communist Party.
In late March 1933, the RWG headquarters, Connolly House in Great James Street, was attacked by a mob, and O'Neill played the leading part in the defence of the building, armed with a woodman’s axe.
On 3 February 1948, a Third Secretary at the US Legation in Dublin, R. M. Beaudry, reported a conversation with Father McLaughlin of Boyle, County Roscommon, who considered that The Irish Press had been infiltrated by "communistic elements", including O'Neill.
He said O'Neill had been born in New Jersey and was also writing for the Communist Party USA’s Daily Worker and was a foreign correspondent for the Soviet news agency TASS.
[13] On 29 April, O’Neill responded, citing Desmond Ryan, Diarmuid Lynch, Maureen Wall, Leon Ó Broin, and F. X. Martin, and insisted that the document had been a forgery by Joseph Plunkett and Sean Mac Diarmada.