Eric Varley correctly foresaw a long barren period ahead with Labour in opposition, and preferred to lead a more positive existence.

After resigning from the Commons in 1984, he became chairman and chief executive of the Coalite Group in his beloved native county of Derbyshire.

By then he had already made a considerable mark as an efficient minister, particularly in the fields of industry and energy.

His abrupt and unexpected departure from the Commons severely weakened the Opposition frontbench. But he was a man of considerable energy who regarded life as an impotent shadow minister as an unrewarding occupation.

He returned to Westminster in 1990 when he was appointed one of five new Labour "working" peers.

Lord Varley was born in 1932, in Poolsbrook, Derbyshire, and brought up in Spike Island, a grim and isolated community ringed by the pitheads and slag heaps of Staveley.

He was educated at a secondary modern school and at Chesterfield Technical College. This was followed by a three-year course at Sheffield University's extra-mural department on economics, industrial relations and political theory.

Varley worked as a craftsman in the mining industry before his election as MP for Chesterfield in 1964.

By then he had already served as branch secretary and area executive committee member of the Derbyshire region of the National Union of Mineworkers.

His abilities as a parliamentarian were quickly spotted, and Varley was made an assistant Government whip in 1967. A year later, he got his first big break, appointed parliamentary private secretary to Harold Wilson himself.

Although a menial task, it thrust Varley right into the very hub of political activity at 10 Downing Street. It was an admirable baptism for his subsequent spectacular but relatively brief political career.

In 1969, he had another break. When Reginald Prentice, later to become a Tory, refused the offer of a job as Technology Minister, Varley had no hesitation in accepting it himself.

And when Labour went into opposition, Varley increased his own stature within the party by becoming chairman of the trade union group of Labour MPs.

He also served as a spokesman on power and was especially effective during the 1974 miners strike which precipitated the downfall of Edward Heath's Conservative government.

Varley then went on to become Secretary of State for Energy and then Industry, a post he held until Labour's defeat in 1979.

At one stage in his career, Time magazine named him as one of its 150 rising stars in world affairs and he was seriously considered as a successor to Harold Wilson.

But the arrival of Margaret Thatcher in 1979, and the fear that dwelt in Varley's mind that Labour would not get back into office for a long time, forced the decision on him in 1984 to quit the Commons altogether.

Lord Varley is survived by a widow and one son.