It is "inconceivable" that the loyalist killing of a Gaelic football fan during the Troubles could have been planned and carried out without the involvement of the security forces, a court has been told.

Sean Farmer, 32, was on his way home from a GAA match when he was shot dead along with his friend Colm McCartney, 22, at a dummy roadblock in Altnamackin, County Armagh, in 1975.

Farmer's family has taken a civil case against the Ministry of Defence (MoD) alleging misfeasance in public office, negligence and trespass to the person.

The MoD denies liability.

During his opening statement at the High Court in Belfast, a barrister for Farmer's family said the victims had been murdered by members of the Ulster Volunteer Force (UVF) known as the Glenanne Gang.

The barrister, Des Fahy KC, described the gang as a group of loyalist paramilitaries which he said included "serving members" of the Ulster Defence Regiment (UDR) and the Royal Ulster Constabulary (RUC).

A civil case taken by the Farmer family against the Police Service of Northern Ireland (PSNI) was settled last week. The family was informed it was to receive undisclosed damages and an apology.

Fahy said on the night of their murders, Farmer and McCartney had been driving home from an All-Ireland semi-final at Croke Park when they encountered "a UDR checkpoint" close to the border, which consisted of men with UDR uniforms, guns and equipment.

He said those operating the checkpoint had then been seen by a witness opening fire on the victims, whose bodies were later found on the side of the road.

Fahy said the plaintiff's case was "that this could only have happened with the active involvement of serving members of the UDR".

The UDR was a British Army unit that operated in Northern Ireland for 22 years from 1970.

Counsel for the MoD said it denied there was any involvement of the UDR or any serving member in the killings.

Mark Robinson KC told the court the plaintiff's case was "based on hearsay and intelligence, and intelligence is not evidence".

He said even if it was established that there was a soldier present at the killings, "they were not acting within their role as a soldier".

Fahy, representing the Farmer family, said there was evidence and intelligence that implicated a serving member of the UDR and a serving member of the RUC in the murders.

He said the men had been "implicated in attacks attributed to the Glenanne Gang", including the murders of Farmer and McCartney, as well as the murders of the Reavey brothers - three men who were shot dead at their home in Whitecross, County Armagh, a few months later.

Fahy told the court that "some of the same weapons were used" in both sets of murders.

"The plaintiff's case is that it is inconceivable that loyalist terrorists could have planned and carried out this attack, using UDR intelligence, equipment and guns, without the involvement of personnel in the service and employment of the second defendant," he said.

The Farmer family pursued legal action after a Historical Enquiries Team (HET) report into the shootings identified "disturbing omissions" and a "lack of any structured investigative strategy".

Former HET investigator Steve Morris was called as a witness before the High Court.

He told the court it was his view that the "vast majority" of the Glenanne Gang were "members of the security forces".

"That was carried out by a number of individuals, some of whom were serving members of the UDR and dressed as the UDR," he said.

The court also heard testimony from one of Farmer's four sons - Brendan Farmer.

He said he experienced anxiousness and started drinking in later years.

The case continues.

The Glenanne gang were members of the loyalist paramilitary group the UVF.

Members operated from a farm in Glenanne, County Armagh, in the 1970s, and have been linked with multiple murders

Its activities were examined by Operation Kenova, who reviewed 98 incidents resulting in 127 deaths.

In a report published in 2025, it stated "an easily defined discrete Glenanne Gang did not exist."

It said the term had evolved to group together "a broader network" of UVF paramilitaries, who acted with "corrupt" members of the police and army.