Lord Callaghan wrote for the BBC News website on the occasion of Labour's centenary in 2000.
Jim Callaghan took office in 1976
In that column, republished here, he told of the challenges he faced in three years at the party's helm.
The newly-formed Labour Party was an intruder upon the political scene a hundred years ago.
Until then, parliament had served the interests of the landowners, of the property owners, of the manufacturing and trading industries.
Democratic election was narrowly restricted to a minority. No more than 60% of adult men and not one solitary woman throughout the country was allowed to vote in parliamentary elections.
The mass of semi-skilled and unskilled wage earners was ill-paid, housed in slums and worked long hours in heavy manufacturing jobs.
Unemployment was widespread and poverty, ill-health and destitution was the fate of the old.
Then a new voice was heard to speak on their behalf.
Trade unionists and Socialist Societies joined together and brought into existence a Labour Representative Committee, whose purpose was to use Parliament to harness the popular instinct for social fairness and individual freedom which courses through the veins of the British people.
The Labour Party can be proud of its part in improving the life of our people during the last century
Day after day, Keir Hardie and a tiny handful of Labour MPs new to Parliament compelled the House of Commons to keep in the forefront of its agenda the shocking conditions of the mass of their fellow countrymen.
And so it has remained ever since.
The Labour Party organised and grew during the early years of the century until in 1945 it became a majority government which put into practice its principles and priorities.
Socialism in action
The welfare state was ushered in with, for the first time, comprehensive national insurance plus a vastly improved pension for the elderly, a free National Health Service for all and compensation for those who suffered accidents at work.
This was socialism in action. Alongside all this, the Labour government introduced freedom from colonial rule for the many millions living in the vast Indian sub-continent.
The last half century has seen success and setbacks. During my period as prime minister, from 1976 to 1979, the parties in parliament were equally divided with Labour forming the government but handicapped by not having a majority.
At that time, the economies of the world were badly hit by the unprecedented hike in Middle East oil prices, inflation was rampant and high prices caused industrial unrest.
But even then and on all occasions since, the Labour government and the party has never ceased to extend its concept of social fairness.
We continually work to remove racial discrimination, to secure equal rights for women in all aspects of their lives, to increase wider opportunities for higher education to our young people.
Today the digital age, with its impact on global finance, requires us to adapt and modernise our institutions to cope with the strains this revolution is throwing on the lives of all the world's peoples.
The Labour Party can be proud of its part in improving the life of our people during the last century.
I am confident it will continue to safeguard and promote those same values and concerns which its pioneers thrust upon the nation's attention a hundred years ago.