There is however an equally long record of conflict between the British establishment and the the particular strand of unionism represented by the DUP.
One significant episode in this story came to light in 1976, when DUP leader Ian Paisley complained in the Commons about the activities of intelligence officials at the Northern Ireland Office.
An affirmation has been made—I affirm this in the House tonight—that there is an attempt in this unit of psychological warfare to discredit and undermine the Loyalist leadership in the Province .
Paisley's allegation was a credible one. The following year, the Sunday Times reported that the Northern Ireland Information Policy Co-ordinating Committee was involved in just such activities.
On the political front, we have discovered that, towards the end of 1974 a committee consisting of representatives from the Northern Ireland Office, the Army, and the Royal Ulster Constabulary met at Stormont Castle and discussed among other things, ways of discrediting politicians judged hostile to Government policy .
The IPCC had been established in part to get a grip on projects that were already being carried out by the Army. In 1990, the Ministry of Defence admitted that Army information officer Colin Wallace may have been authorised to carry out disinformation activities. The strongest assurance Minister Archie Hamilton could give the Commons was that 'It has not since the mid 1970s been the policy to disseminate disinformation in Northern Ireland in ways designed to denigrate individuals and/or organisations or for propaganda purposes' 
This was not the only occasion during 1976 when the DUP pushed back against what it saw as Whitehall operations against it.
Towards the end of the year, DUP member Clifford Smyth was expelled from the party, over alleged contacts with the Northern Ireland Office. He later recounted:
In November 1976 I had been called to a meeting in Ian Paisley's Parsonage where I would be accused of passing on information to Merlyn Rees's office at Stormont and of having compiled a document which made scandalous allegations about leading loyalist politicians. Ian Paisley was irate and the whole atmosphere was deeply hostile. Nothing had prepared me for this. I didn't know what was going on. I was mystified but some of the information that I was aware of, had come from the lips of Ian Paisley's paid employees. I felt there was little alternative but to take whatever was coming to me however unfair the situation might be 
Smyth denied the accusation, but in his later book on Paisley, he claims to have some heavily compromising information on the DUP. He states that in June 1976, the party secretary Peter Robinson told him that the DUP should form its own paramilitary force (something that would occur a decade later with the formation of Ulster Resistance) .
Smyth goes on to note that he had some experience of the paramilitary world, having been approached at one time to join the UVF . This was probably a result of his role as intelligence officer of Tara, a shadowy group run by the paedophile William McGrath .
As with Clockwork Orange, there is evidence to substantiate DUP suspicions about official surveillance. If Smyth was not passing information to the authorities, someone else close to William McGrath was doing so at around the same time.
In his book The Kincora Scandal, journalist Chris Moore described how an army officer he called 'James' made contact with two individuals with information on Tara in the mid-1970s. One was 'Sydney' a politically astute and well-informed Tara member, the other was Roy Garland, a former member who was trying to expose William McGrath's sexual proclivities .
When James put Garland's allegations to the political advisor at HQ Northern Ireland, he was peremptorily ordered to break off contact with both sources. Contacts with Sidney, though not Garland, resumed following a meeting in 1976:
With approval from his authorities, James set off to a Belfast cemetery for the meeting and what he learned there was to make him the political advisor's 'blue-eyed boy'.Sidney informed James that certain political figures were seriously examining the possibility of UDI and in the short-term were planning an announcement to that effect .
The Historical Institutional Abuse Inquiry, which reported earlier this year, confirmed many of the details of this story. it made clear that 'James' was Captain Brian Gemmell, and that the political advisor was Ian Cameron of MI5. It confirms that Cameron and Gemmill discussed a second source as well as Garland . This source is referred to as 'an agent whose identity is known to the Inquiry' suggesting that, unlike Garland, he was formally recruited by army intelligence .
The inquiry says very little else about this other source, but the evidence strongly suggests it was 'Sidney'. MI5 documents disclosed to the inquiry show that an agent close to McGrath was debriefed following the exposure of the Kincora scandal in 1980. The agent admitted to MI5 officers that he had told McGrath of his relationship with them, possibly in 1976 .
The question that the HIA Inquiry never addressed is this: If MI5's agent feared a threat to him in the aftermath of McGrath's exposure in 1980, could his recruitment have given MI5 a motive to protect McGrath earlier?
If the agent was 'Sidney' he was himself a member of Tara, and one who claimed to have have heard that McGrath was working for MI5. This raises a number of other questions.
Did the HIA Inquiry ever seek to question Sidney about this, assuming he is still alive? Did the inquiry give Sidney an assurances in relation to the Official Secrets Act? What did Sidney tell MI5 about Tara's activities, including its involvement in loyalist arms dealing and overseas paramilitary contacts?
Finally, there's the issue of who exactly were the politicans plotting UDI that 'Sidney' was reporting on. Given the eclipse of William Craig's Vanguard the previous year, the major force to the right of Ulster Unionism in 1976 was the DUP, which was indeed gearing up for a challenge to the British state, the United Unionist Action Council strike of 1977, backed by the UDA and other paramilitary groups. Was Sidney's information instrumental in the strike's failure?
This covert intelligence struggle between the NIO and the DUP, which seems to have spanned both Labour and Conservative Governments, may be one reason why neither side in the Tory-DUP deal was anxious to look too closely at the past activities of the state.
 Hansard, House of Commons Debates, 19 February 1976, vol 905, cc1653-64. <http://hansard.millbanksystems.com/commons/1976/feb/19/northern-ireland-office#S5CV0905P0_19760219_HOC_481>.
David Blundy, The Army's Secret War in Northern Ireland, Sunday Times, 13 March 1977
Hansard, House of Commons, 30 January 1990, Written Answers to Questions, cc108-110. <https://publications.parliament.uk/pa/cm198990/cmhansrd/1990-01-30/Writtens-2.html#Writtens-2_sbhd19>.
 Clifford Smyth, Dealing with my sexual brokenness, 20 July 2005. <http://www.belfasttelegraph.co.uk/imported/dealing-with-my-sexual-brokenness-28223912.html>
 Clifford Smyth, Ian Paisley: Voice of Protestant Ulster, Scottish Academic Press, 1987, p.106.
 Ibid. p.108.
 Chris Moore, The Kincora Scandal, Marino books, 1996, p.73.
 Ibid. pp.16-139.
 Ibid. pp.142-143.
 Report of the Historical Institutional Abuse Inquiry, Chapter 28: Module 15 – Kincora Boys’ Home (Part 2), Ian Cameron, Roy Garland and Brian Gemmell, pp.42-46.<https://www.hiainquiry.org/sites/hiainquiry/files/media-files/Chapter%2028%20-%20Module%2015%20-%20Kincora%20Boys%E2%80%99%20Home%20%28Part%202%29.pdf>.
 The relevant MI5 reports are archived at Powerbase:
29 April 1980. <http://powerbase.info/images/2/2f/HIAInquiryMI5extract2.pdf>
See also my article: Loose ends from the Hart Inquiry - significant evidence from the RUC and MI5, Spinwatch, 27 February 2017.