Forensics experts were investigating an explosion in the village of Ballyeaston in July 1966.
The blast, which was heard three miles away, shattered 30 windows within a 30 yard radius.
Panes of glass in a telephone box, where the explosion was believed to have occurred, were also smashed.
“I thought the whole town had been blown up,” said Alexander Agnew, owner of the Ballyeaston Post Office.
“It was a great shock. This is normally a quiet village.”
Another villager, James Dunlop, said that he had been awakened by the loud bang.
“Three windows in my house were blown out,” he said.
In response, police officers made inquiries and carried out interviews in the village.
Meanwhile, a post box at the junction of Doagh Road and Straid Road, which had been demolished in a road traffic accident, was not to be replaced.
The Post Master General pointed out that just a dozen letters were posted in the box daily.
He indicated that another post box was located 200 yards along the road.
He also noted that a review of postal arrangements in the district was pending.