Benjamin Disraeli's idea that deep divisions between rich and poor halves of a nation are unacceptable.
The one nation tradition has been one of conservatism’s most elevating themes since introduced to the national conversation by Benjamin Disraeli in his landmark 1845 novel - Sybil.
Disraeli wrote about:
"Two Nations Between Whom There Is No Intercourse And No Sympathy; Who Are As Ignorant Of Each Other's Habits, Thoughts, And Feelings, As If They Were Dwellers In Different Zones, Or Inhabitants Of Different Planets; Who Are Formed By A Different Breeding, Are Fed By Different Food, Are Ordered By Different Manners, And Are Not Governed By The Same Laws."
In his writings, and subsequently as Prime Minister, Disraeli began the One Nation Conservative tradition that seeks to include every willing person in the life and opportunity of Britain.
Is Britain one nation today?
The material squalor of Disraeli's times has gone from Britain. Our country has never been more materially prosperous. State spending on crime-fighting, health, education and welfare has never been higher. Technology advances at an accelerating rate.
Yet despite these advances, a range of social problems persist. Family breakdown, drug addiction, patterns of self-harm, loneliness, rates of sexually-transmitted infection - these problems may be concentrated in poorer neighbourhoods but they are increasingly spreading beyond boundaries of place, ethnicity and income.
It wasn't supposed to be this way. As we grew wealthier, technologically more sophisticated and more able to afford a larger welfare state, social problems were supposed to melt away. Many have. But others have become more ingrained and still others have emerged.
Europe, Tony Blair and compassionate conservatism
Towards the end of the Thatcher-Major years the idea of one nation Toryism became associated with the Europhile wing of the Conservative Party. On one occasion Mrs Thatcher even accused one nation Tories of being no nation Tories. A great Conservative tradition was being lost in internecine disputes over Europe.
Never one to miss an opportunity, Tony Blair commandeered the term ahead of his 1997 victory. He claimed that New Labour had become the inheritors of Disraeli's mantle. That was always a stretch and Tories have belatedly begun to fight back.
Compassionate conservatism - and its emphasis on family structure, school choice, harm avoidance and zero tolerance policing - offers progressive Tories the opportunity of reclaiming the one nation idea.