[4][5] His brother, Emmet Stagg became a Labour Party politician and a Teachta Dála (TD) for Kildare North.

[6] In 1972, he joined the Luton cumann of Sinn Féin and soon after became a volunteer in the Provisional Irish Republican Army (IRA).

[7] In April 1973, Stagg was arrested with six others alleged to comprise an IRA unit planning bombing attacks in Coventry.

[7][6] Following the hunger strike that resulted in the death of Michael Gaughan, the Price sisters, Feeney and Kelly were granted repatriation to Ireland.

On 14 December 1975, Stagg embarked on a hunger strike in Wakefield, along with a number of other republican prisoners, after being refused repatriation to Ireland during the IRA/British truce.

His widow, his brother Emmet Stagg and the Irish government wished to have him buried in the family plot in the same cemetery and to avoid republican involvement in the funeral.

This first burial was attended by thousands of Republicans while 1,600 members of the Irish Defence Forces and the Garda Síochána were deployed by the government to keep order at the funeral.

Despite their presence, members of the Provisional IRA attended this first burial, firing volleys of shot over his coffin, in the style of a military funeral.

Joe Cahill, who had formerly been a Chief of Staff of the IRA, attended the ceremony and vowed during it that at some point in the future there would be another funeral for Stagg, with his body being laid to rest beside that of Gaughan's.

Stagg's widow Bridie and his brother Emmet were reported to have been intimidated by members of the Provisional IRA due to their opposition to his burial in a Republican plot.