Sergeant Mannix of the DMP station at Donnybrook was particularly valuable. He secured names and addresses of British Secret Service Officers who were later shot on “Bloody Sunday”. As a result, Collins was able to get an IRA hall porter placed in one of the houses and hall doors and room keys were obtained for all the others. Detailed reports were prepared on each agent. Thornton’s job was to collate the information. He also got the unenvious job of presenting his full reports to a joint meeting of the Dail Cabinet and Army Council, at which he had to prove that each and every man on his list was an accredited Secret Service man of the British Government.
"I was on several occasions detailed for duty at the Show Grounds, Ballsbridge, and subsequently had to accompany British Officers from the Show Grounds who were engaged in searching houses in the Donnybrook area. On a few occasions while ccompanying the search parties , I saved the lives of men who were found in the houses that were being searches, as I informed the officers in charge that these were law abiding citizans, though in each case they were much wanted men. The officer, relying on my information, then withdrew, and the men got safely away. I remember on one occasion I was with a search party. The officer in charge being Lt Brookbank, who was arrached to the Royal Irish Rifles. He knocked at the door of a certain house, and when the door was opened I saw a number of men playing cards. One of whom I knew to be a very much wanted man. I informed the officer that they were all friends of my own, and we retired leaving the men to escape. He also knocked at the door of another house where a much wanted man was residing. He escaped before we entered. The following day he was observed by a Secret Service Agent who immediately informed Donnybrook Station ..Everything was in readiness for the raid that night" Mannix got word to the man, who got away before the raid took place