On Saturday 14th May 1921 she was involved in the Coolbaleen Ambush while motoring in the car driven by District Inspector Biggs. Miss Barrington and Miss Coverdale, who was a guest at Glenstal Castle (the Barrington's home) went into Newport. Miss Barrington rode on a pony and Miss Coverdale cycled. In Newport, Miss Barrington and her friend met Mr. Gabbett, who was a friend of the Barrington family, Major Biggs, and Captain Trengouse. The pony and bicycle were left in Newport, and five set out in a private car, they apparently went for tea in someone's house. On the return journey, and when between Kiloscully and Newport, at about half past seven o'clock, the car was suddenly ambushed at Coolboreen bridge.
Her evidence to the Military Inquiry was:-
[Miss Coverdale] stated that they motored to a house where they had tea. On the return journey, and when they got to Coolboreen bridge, fire was opened from both sides of the bridge and behind. Captain Biggs, who was driving, was hit in the throat, and the car stopped after going a few yards. The three men jumped from the car and ran up the road, Miss Barrington was thrown on to the road and remained there. The firing went on, and seven or eight shots struck the back of the car where witness was, and she was wounded. She saw Captain Biggs running about ten yards from the side of the car and then drop, with [Mr Gabbett] and [Lt Trengrouse] standing alongside him on his right. [Lt Trengrouse] then got through a hedge and fired his revolver at the attackers. She saw him then running away. The firing continued, and she heard [Mr Gabbett]say, "Stop, stop; there is a lady in the back of the car". [Mr Gabbett] then went to help Miss Barrington, who was lying on the side of the road, and witness stood up in the car with her hands up. She then saw about five or six men come up. The leader asked how many were in Biggs' car and who was lying on the road. Witness told him it was District Inspector Biggs. He then asked where the other was, and she replied that she did not know. She told him there was a girl lying on the other side of the road, and he said it served them right for driving with the military. At that time Miss Barrington was unconscious but alive. She asked for help, and the reply she got was that it served them right. She saw in all about a dozen men there, and some of them before they left went up to where Captain Biggs was lying and fired at him. Witness remained with Miss Barrington until the military arrived, and before the attackers left they fired over their heads.