A series of memorial events will mark the 40th anniversary of the murders of the former Stormont Speaker Sir Norman Stronge and his son James.
ir Norman (86) and his son (48) were shot dead at their home, Tynan Abbey, in Co Armagh, on January 21, 1981.
The pair were killed by an IRA gang who then firebombed the isolated mansion, located a few miles from Caledon, and the resulting blaze left the historic building in ruins.
Both men were leading figures in the Royal Black Institution, which is planning events in 2021 to mark the anniversary.
The Institution's current Sovereign Grand Master, Rev William Anderson, said: "The heinous murders of the highly-respected Sir Norman Stronge, an elderly man at the time, and his son, were wicked, despicable and cowardly.
"The killing of two defenceless men in their own home was, sadly, yet another example of the depravity and blood-lust of the republican killing machine which wreaked havoc and brought misery to countless families throughout the Troubles.
"The emotional wounds from the double murder are still keenly felt by members of our Institution, and it is our intention to remember both men with pride and affection in the New Year."
Sir Norman was a member of RBP 264 Breaghey and was Sovereign Grand Master of the Royal Black Institution from 1948 to 1971. He was also a senior Ulster Unionist Party politician.
He had previously served as a junior officer in the Army during the First World War. He fought in the Battle of the Somme in 1916 and was awarded the Military Cross. His positions after the war included a 23-year term as Stormont Speaker.
Sir Norman's son James Stronge was also a member of RBP 264 Breaghey.
In 1967, he was appointed High Sheriff of Armagh. He served as Ulster Unionist MP for Mid Armagh for three years until the prorogation of Stormont in 1972 and as a member of the Northern Ireland Assembly from 1973 to 1974. He was also an officer in the Grenadier Guards.
Having withdrawn from political and military life, his main interests were confined to merchant banking and his service as an RUC Reserve Constable.
Details of the Royal Black Institution's memorial events for Sir Norman Stronge and his son will form part of the Royal Black Institution's "Time to Remember" season.
Rev Anderson added: "The Institution's Stronge Memorial Project will provide a basis around which we can explore and celebrate our country's rich history.
"The Stronges embodied two principles which have proven to be integral to our country's character: service and sacrifice."
Government papers released in 2012 outlined events leading up to the murders.
They detailed how an armed gang of 10 men crossed the border, hijacked two vehicles and went to the Abbey, where they murdered Sir Norman and his son, before setting the Abbey on fire. The IRA said it was a reprisal for recent attacks by loyalists on republicans.
The last surviving child of Sir Norman, Evelyn Elizabeth Olivier (nee Stronge), known as Evie, passed away in 2018 aged 93.