Lord Harris of High Cross, pioneer of Thatcherism and outspoken eurosceptic, has died at the age of 81.
Lord Harris was a pro-smoking campaigner
His death on Thursday was announced by the Institute of Economic Affairs (IEA) where he was a founding director from 1956 to his retirement in 1988.
He had suffered a suspected heart attack at his north London home.
Ralph Harris was the first lord appointed by Margaret Thatcher and sat as a cross-bencher. He was also president of smokers' group Forest.
He developed a distinguished career as an economist and writer and came to be considered a "chief architect of Thatcherism".
In founding the IEA he was credited with encouraging countries around the world to explore market-based approaches to solving economic and social problems.
He served as chairman of the Bruges Group, an independent all-party think-tank that campaigned against economic and monetary union between the UK and Europe.
But he was equally outspoken after joining Forest, becoming the organisation's president in 1987.
Describing himself as a "lifelong pipe-man", he was an enthusiastic supporter of smokers' rights, writing numerous essays and even a book, Murder A Cigarette, in 1998.
He also campaigned against banning smoking in public places.
He once said: "A lot of people fulfil themselves through sucking at their pipes or smoking their fags. It's part of their personality."
Tory peer Lord Tebbit said: "This is a very grave loss. He was a unique figure, always full of common sense, which is, in fact, most uncommon.
"I am just sad that he is no longer there. I valued him as a friend and a source of inspiration and advice."
Lord Harris was educated at Tottenham Grammar School and Cambridge, where he won a first in economics.
He spent a period as a lecturer at St Andrews University, during which time he also twice unsuccessfully stood in Scottish seats for election to Parliament.
He is survived by his wife Jose, who he married in 1949, and a daughter.