Captain Frederick John Holroyd was a British soldier who was based at the British Army's 3 Brigade HQ in mid-Ulster, Northern Ireland during the 1970s. He enlisted as a gunner in the Royal Artillery, and three years later, in 1964, he was commissioned into the Royal Army Service Corps (later the Royal Corps of Transport). He volunteered for the Special Military Intelligence Unit in Northern Ireland in 1969, and he was trained at the Joint Services School of Intelligence. Once his training was finished, he was stationed in Portadown, where, for two and a half years up to 1975, he ran a series of intelligence operations. He resigned from the Army in 1976.
Holroyd described a policy of assassinations and collusion between the British Army Intelligence Corps and Ulster loyalist paramilitaries in Northern Ireland. Holroyd was one of a number of former members of British forces who either exposed or admitted to such activity, the most prominent being Colin Wallace and John Weir (see Dublin and Monaghan bombings).
Holroyd also claimed that during the mid-1970s the Special Air Service (SAS) used the cover name, "4 Field Survey Troop, Royal Engineers" (see 14 Intelligence Company) during operations. This modus operandi was introduced in 1973 and abandoned in 1975. Fred Holroyd claimed this was an SAS unit under cover at the Royal Engineers' base at Castledillon, County Armagh, which he visited (see 14 Intelligence Company). Holroyd said he worked with the members of this unit and that members were told that it was a NITAT (Northern Ireland Training and Tactics Team), whose personnel were "former, serving or recently trained" SAS soldiers, with the commanders being infantry officers attached to the SAS. One of these was Captain Robert Nairac, described as, "seconded to 14th Intelligence", otherwise known as 14 Intelligence Company" or '14 Int'.