William Craig: Unionist politician who started out as a moderate but moved to extremism during the Troubles

William Craig was one of the most important unionist politicians during the first decade of the Northern Ireland troubles. Indeed, he was accused of instigating them by ordering police to break up a civil rights march.

The extraordinary trajectory of his career saw him lurch – he drank a lot – from stern pillar of law and order to a dangerous dissident who publicly threatened to assassinate opponents. In a final twist he astounded everyone by advocating a form of cross-community power-sharing which was, for its time, so radical that other unionist leaders instantly expelled him from the Protestant political mainstream.

By the early 1980s he was gone from public life. In retirement he never admitted that the graphic images of police attacks on Catholic marchers in Londonderry had inflicted a grievous, game-changing blow to the unionist cause. "I thought the way the police acted was fair enough," he maintained."I would have intensified it. I wouldn't have given two hoots for the Labour MPs who were present, or the TV pictures."

As his comments suggest, he often lacked rudimentary political skills such as judgement, restraint and an appreciation of public relations. Yet in the earlier part of his career he was looked on as a talented, steady pair of hands as he rose steadily though the ranks of the Unionist Party which controlled Northern Ireland. Born in County Tyrone in 1924, Craig joined the RAF and served as a rear-gunner in Lancaster bombers. Later he qualified as a solicitor, becoming active in the Young Unionists while at Queen's University, Belfast.

Elected to the Belfast parliament in 1960, he quickly entered the upper reaches of Unionist politics even though he was not amongthe "Big House" landowners who dominated the party. As chiefwhip he engineered the succession to the premiership of CaptainTerence O'Neill, a mild reformerwho rewarded him with a series ofsenior ministries. For some yearsthey had a fruitful relationship until O'Neill sacked him for political insubordination.

That was in Craig's rebellious, truculent phase. But in the early period he was seen as moderate and even progressive, with a lively interest in Europe and the rest of the world. O'Neill was to write that Craig "gradually changed from a forward-looking person, interested in continental and international affairs, into a narrow-minded sectarian."

That judgement of Craig was largely based on his conduct in 1968, with the arrival on the streets of the civil rights movement which complained that unionism systematically discriminated against Catholics and nationalists. As Minister for Home Affairs Craig banned a Londonderry march, a move which swelled the numbers attending it. The police used water cannon and batons on an obviously peaceful group of marchers on an occasion regarded by many as marking the onset of the troubles. The televised scene shocked the world, galvanising the British Labour government into pressing O'Neill to extend and accelerate his reform programme.

Craig dismissed the civil rights movement as bogus and a front for the IRA. "All this nonsense centred around civil rights," he rumbled, "and behind it all there is our old traditional enemy exploiting the situation."

He not only opposed all moves towards reform but went further. Flying in the face of the constitutional – and financial – facts of life, he asserted that Westminster had no right to impose its will on the Belfast government. After he delivered several defiant speeches O'Neill sacked him, accusing him of wanting to become independent of Britain and rebuking him: "Your idea of an Ulster which can go it alone is a delusion."

Later, when O'Neill was forced from office, Craig stood for the party leadership but was soundly beaten by 26 votes to four by Brian Faulkner, who was regarded as a cleverer and more professional politician. When London abolished the Belfast parliament Craig became more and more hard-line, often co-operating with other figures such as the Rev Ian Paisley in opposing any form of accommodation.

He formed a group called Vanguard which staged a series of "monster rallies" at which he would arrive, melodramatically flanked by motorcycle outriders, to inspect thousands, and sometimes tens of thousands, of men drawn up in military-style formation. His statements caused much alarm. During one speech he declared: "I am prepared to come out and shoot and kill. I am prepared to kill and those behind me will have my full support. We will only assassinate our enemies as a last desperate resort when we are denied our democratic rights."

His aides privately said he was drunk when he made that particular pronouncement: O'Neill commented drily that he had "a fatal fluency of speech". But Craig was certainlyprepared to associate openly withloyalist paramilitary groups. That was in 1972, when the death toll of almost 500 included many killings carried out by loyalists.

He built up a substantial vote but never managed to establish a decisive lead over rivals such as Paisley. This was partly because many unionists, priding themselves on being law-abiding citizens, were highly uncomfortable with his fiery outbursts and alliances with gunmen. By 1975 he had a long-established reputation for inflexibility. It therefore came as a total surprise when he advanced the proposal, known as voluntary coalition, that a restored unionist administration could invite moderate nationalists into government on a temporary basis.

Today this looks like a fairly modest proposal but it was angrily denounced by other unionist leaders, who were holding out for a return to straightforward majority rule. The Vanguard party fell apart, most members abandoning Craig.

His later attempts to stage a comeback came to nothing. He had become a Westminster MP in 1974 but lost the seat five years later to Peter Robinson, who took a tougher line. But times change; unionism has mellowed; and today Robinson, as Northern Ireland's First Minister, amicably shares power not only with moderate nationalists but also with Sinn Fein.

William Craig, solicitor and politician: born Cookstown, County Tyrone 2 December 1924; married 1960 Doris Hilgendorff (two sons); died Bangor, County Down 25 April 2011.