Few leading trade unionists of his era experienced such fluctuations of public image as Jack Jones did, and few stuck more grimly to their guns, even when these appeared to be well and truly spiked.

A year before his retirement as general secretary of the Transport and General Workers Union in 1978, a Gallup poll recorded a majority view that Jones was “more powerful than the Prime Minister”.

As leader of the UK’s largest trade union he had contributed uniquely to the incomes policy set out under the “social contract” between the union movement and the Labour Governmment in 1974. The policy served to compress differentials in favour of most, but not all, general workers. Jones’s ideas were writ large in the mass of industrial relations legislation during the same period. The majority of the Bullock committee on industrial democracy, on which he sat, came out in its 1977 report for elected employee directors on the boards of large companies as Jones had advocated, in Tribune and elsewhere, for a dozen years.

By April 1978 the climate had significantly changed. The minority Government of James Callaghan, propped up by a pact with the Liberals, was considering plans to encourage employee share schemes (which Jones abhorred), and the Bullock proposals had been lost in a series of departmental revisions. The incomes policy Jones had fervently supported was repudiated by the biennial conference of his own union, and he had had to advocate at the Trade Union Congress an approach he was well known to oppose.

By a small coup de théâtre at the same congress, the TGWU was temporarily expelled from the TUC on account of a dispute with the diminutive National Association of Licensed House Managers, which had been admitted to membership in spite of years of TGWU opposition. At the same time, no doubt in reaction against the apparent upsurge in union power during the preceding three years, TUC influence in general was increasingly discounted in Whitehall.

Jones was no stranger to such reversals of fortune. He first became active as a trade unionist in the early 1930s when membership was at its lowest of the century. He saw its influence rise during and after the Second World War, subside in the 1950s and rise again in the 1960s. During all this time he followed his own heavy logic. He spent 39 years as an employee of the union, saw it reach a membership of nearly two million during his term of office and bossed and bargained his way to a distinctive niche in labour history.

Solid, commanding and ascetic — a more raffish colleague once chaffed him as being “everything short of teetotal” — Jones had a clear view of the industrial world and the place in it of the country’s largest trade union. Although he was habitually identified with “the Left” both inside and outside his union, a view reinforced by the sequence of events that brought him to the head of it in 1969 when he was 56, his formidable institutional loyalty was perhaps the dominant feature of his career.

Jones was a curious combination of the romantic and the humdrum. Born on Merseyside in 1912, he was christened James Larkin Jones after the Liverpool Irish socialist, and to the end of his life loved to quote the writings of Pearse and Connolly, the socialist martyrs of the Easter Rising in Dublin in 1916. Yet he was no orator himself, even at a time when consciousness of his power lent weight to what he had to say, and his heavy delivery added nothing to the harsh poise of the workplace that had shaped it. And although he went to war for his ideals as a young man, the successes of his career came from obdurate negotiation, bureaucratic competence and a flair for taking the chair.

Jones started work on Garston docks in 1927; a year later, before he was 16, he was secretary of his ward Labour Party, and at 23 he became the youngest member of Liverpool City Council. Of the Left, although never a member of any party but Labour, Jones volunteered for the civil war in Spain. He crossed the Pyrenees on foot to reach Catalonia where he joined the International Brigade and first saw action near Lerida with the Spanish Army. He served for more than a year until wounded by a bullet in the right shoulder at the Battle of the Ebro in 1938.

“I had been given a black leather jacket before going to Spain,” he recalled. “Foolishly I insisted on wearing the bloody thing, which made me rather more visible than others.”

He retained his hatred of the Franco regime and after he had become national leader of his union, attracted criticism over his forthright lectures to colleagues whom he suspected of holidaying in Spain.

In 1938 Jones married and moved to Coventry, where he was appointed district secretary of the Transport Union. His wife, Evelyn, an ebullient activist when women were still rare in that role, went to work at the old Standard Motor Company and became a shop steward. Jones himself worked systematically on a dossier of wage rates, company performance and shopfloor contacts. He encouraged the development of shop bargaining, against the wishes of most employers and many of his union colleagues. He was unsparing in negotiation and totally without the small talk and sociability that softened the style of more traditional union bargainers.