Michael Foot, the most improbable literary romantic to lead a major British party since Benjamin Disraeli, has died at the age of 96 after a turbulent political career that left him a much-loved but also deeply controversial figure.

A brilliant orator, steeped in Swift, Byron, Shelley and the great political struggles of the 17th century, Foot was first an incorrigible rebel who helped foster the left-right Bevanite split that damaged Labour throughout the 50s. A champion of British unilateral nuclear disarmament, one of the left's great postwar causes, he gradually moved towards office in the economic crisis of 1974.

Foot led Labour from 1980 to 1983, presiding over the party during the formation of the breakaway SDP. He resigned after Labour fell to a stunning defeat in the 1983 election, the voters having rejected a manifesto later called the "longest suicide note in history".

In a statement, Gordon Brown said: "Michael Foot was a man of deep principle and passionate idealism and one of the most eloquent speakers Britain has ever heard.

"He was an indomitable figure who always stood up for his beliefs and whether people agreed with him or not they admired his character and his steadfastness."

Tony Benn, his cabinet colleague and occasional nemesis, added: "He was one of the great figures of the Labour movement."

Foot's gallant reputation and prestige kept the left and the unions on side during his time as Jim Callaghan's deputy PM in difficult years from 1976 to 1979. He was also accused of irresponsibility and – ironically in view of his past – of appeasement of the unions by resurgent Conservatives and some Labour MPs.

For others his idealism, which included a life-long devotion to Plymouth Argyle FC, was highly attractive. Despite the defeat of many of his most cherished causes, he had a rich and deeply fulfilled life, which he shared, until her death in 1999, with his beloved wife, the filmmaker Jill Craigie.

In the crisis that followed the defeat of the Callaghan government and the rise of Margaret Thatcher, Foot led the Labour party from 1980 to 1983, presiding over it during the formation of the breakaway Social Democratic Party (SDP), which used his election over Denis Healey as the excuse for their defection.

He stepped down in favour of his protege Neil Kinnock after Labour slumped to a stunning 145-seat defeat in the 1983 election in the wake of a manifesto that a Labour colleague called "the longest suicide note in history". It fell to Kinnock to rebuild his party and put it on the road to three election wins under Tony Blair. Foot, who refused all honours including a peerage, must often have been unhappy with Blair's leadership, but in old age loyalty to his party was a paramount consideration.

It was not always so. The frail child of a West Country Liberal dynasty, Foot was always a rebel, who hitched his star early to the charismatic Welsh ex-miner, Aneurin Bevan, whose admiring biographer he became. Their radical socialist views did not prevent either of them becoming allies of Lord Beaverbrook, the Canadian press tycoon, owner of the then-mighty Daily Express, who shared their sense of mischief.

A distinguished writer and journalist with a passion for literature as well as politics, Foot gained his first great claim to fame as the author of Guilty Men, the celebrated polemic against the prewar appeasers in 1940. Beaverbrook entered Churchill's cabinet, Bevan attacked Churchill, and Foot briefly edited Beaverbrook's London Evening Standard – though the leftwing weekly Tribune was his life's love.

Tribune helped set the tone for Labour's victory in 1945 when Foot, alone in his Liberal family, unexpectedly won Plymouth Devonport for Labour and became a Westminster gadfly. It was a role he maintained from outside after losing Devonport in 1955 and resumed after succeeding Bevan in Ebbw Vale after his hero's death in 1960.

Foot and Bevan fell out over Bevan's renunciation of unilateralism. But Foot followed his mighty heart for much of his career. His firm support of Indian independence led him to back his friend Indira Gandhi when she declared a state of emergency in the 70s. In the 60s he joined forces with Enoch Powell, with whom he shared the title of best parliamentary orator, to block Labour efforts to reform the Lords – though he wanted it abolished, Powell wanted it left untouched.

Such quixotic behaviour prompted his old Oxford friend Barbara Castle to complain that he had "grown soft on a diet of soft options". But when Labour unexpectedly took power again in the global energy crisis – and domestic crisis between Ted Heath's government and the miners – Foot accepted the tough job of employment secretary under Harold Wilson. Under Jim Callaghan, as Labour lost its majority after 1977, he was leader of the Commons and deputy PM, fighting night after night to keep the government afloat.

Among his many gallant defeats of that period was the campaign in which seven cabinet ministers, including Foot, were allowed to fight for a "no" vote when Wilson offered voters a referendum on Britain's still-new EU membership in 1975. The yes camp – which included Margaret Thatcher – won by a ratio of 2:1.

He and Benn were not peas in the same pod and Foot felt personally betrayed when Benn insisted on contesting Healey's role as deputy Labour leader in 1981 – a divisive contest that Healey narrowly won when young leftwingers like Kinnock refused to back Benn.

After his leadership Foot stayed in the Commons backing Kinnock against Militant entryism for which his earlier tolerance had been criticised, until 1992 when his protege lost the general election to John Major. But his passion for books, as for Plymouth Argyle, never dimmed as the infirmities of old age took their toll.

In the bloody 90s when Yugoslavia was torn by civil war Michael and Jill Foot went there and made a film on behalf of their beloved Dubrovnik. No puritan, Foot was fond of drink and laughter as well as ancient historical ports. It was a fitting last hurrah.