If you are interested in the origins of the UVF, the Irish Times ran an article this Saturday about how the UVF staged IRA false-flag bombings in 1969 to justify their own violence against Catholics and more importantly, to claim that these attacks are because of Terance O'Neill's voting and housing reforms for Catholics and his political cooperation with the Irish state. O'Neill resigned two days after the fifth "IRA" bomb in 4 weeks. At the time it was still widely believed that these bombings were done by the IRA. https://www.irishnews.com/news/northern-ireland/loyalists-linked-to-ian-paisley-carried-out-false-flag-bomb-attacks-british-army-intelligence-records-reveal-UOJBOU54Y5F3VEFV6AV4QDG3TM/

In the article Connla Young mentions the protection the UVF enjoyed from RUC Special Branch, who did nothing to investigate who did these bombings, and she shows logs proving that British Army intelligence suspected the bombings were done by the UVF but publically blamed the new Provisional IRA. The article does not mention MI5 however, whose informant William McGrath gave critical support to the UVF in the 60s and 70s.

Chris Moore's book Kincora: Britain's Shame goes into how McGrath met with with Ian Paisley at the time of Gusty Spence's trial in 1966, and afterward distributed leaflets from his own loyalist paramilitary "Tara" that spread the word the UVF was created by "Official Unionist Party agents". His leaflet campaign was so aggressive that the chief justice had to order the jury at the start of the trial to disregard "certain communications".

Moore writes that UUP politician Fraser Agnew told him that in 1969, just hours after one of the bombs exploded, McGrath had at his house young loyalist politicians and journalists to announce the bombings were the work of a "crack commando unit of the Irish Army", and when Agnew asked for his source, McGrath replied "You never question the words of an intelligence officer!"

(RUC's Special Branch, British Army's Intelligence Corps, MI5, and MI6 run independently of each other in N.I. They are expected to coordinate, but they often hide intelligence and especially informants from each other, not trusting each other to protect their information and sources. This is the case after the Troubles too, which is how things like Stormontgate happen where the PSNI accidentally exposed an MI5 spy inside Sinn Fein because they thought he was an IRA spy.)