Lord Chitnis of Ryedale: Liberal Party stalwart who went on to head the Joseph Rowntree Trust

Pratap Chitnis, who has died of cancer, was a Liberal strategist, a radical member of the House of Lords and a highly effective chief executive of a Quaker trust. He had more influence on British politics than was apparent at the time. He was more interested in putting ideas into practice than in formulating them – though it should not be thought, as has been suggested, that he was uninterested in policy and values. He was deeply concerned about social values at home and repression abroad. Every speech of his in the House of Lords and the whole thrust of the Joseph Rowntree Reform Trust's work during his 20 years as chief executive was designed to diminish inequality, protect the vulnerable and ensure that the politically dispossessed achieved political influence.

Pratap Chitnis was a very conservative Roman Catholic. Born in London of Anglo-Indian parentage, he was sent away from London aged three at the outbreak of war into the care of nuns. From there he went to Stonyhurst, the Jesuit college. His education had a deep effect on Chitnis. and he became a deeply religious man. He supported the Latin mass as it ensured that a believer anywhere in the world would be "at home". He saw no intellectual problem in being by faith a conservative catholic and by politics a radical social Liberal.

He joined the Liberal Party after attending a rally at the Royal Albert Hall. Chitnis was impressed by Jo Grimond's speech and was so amazed that a party he thought dead and buried could pack the Albert Hall, that he joined it.

He was enlisted as a candidate in the 1959 municipal elections. With five candidates from each party, Chitnis finished 15th and last. It was his first and last candidature. Four months later he was the general election agent for Michael Hydleman in South Kensington where Sir Oswald Mosley was standing. Hydleman was Jewish, Chitnis of an Indian background. They were met with an unpleasant, sometimes violent response.

Early in 1960 Chitnis was appointed as the party's first local government officer. He set about tracking down every Liberal municipal representative so they could be mailed regularly and visited occasionally. This was less simple than it sounds; sometimes a Liberal councillor could only be identified by contacting the local press using the devious pseudonym of the "Municipal Research Association".

The department's work expanded and in 1962 I joined Chitnis as his assistant. He had been made agent for the Orpington by-election. He took me to three meetings in London to show me "what we do" then announced that he was leaving for Orpington.

His role at the by-election was crucial. He designed and implemented a master plan, with day-to-day organisation delegated to three full-time sub-agents, and took key decisions, such as keeping the inexperienced Eric Lubbock off media events with the articulate Conservative candidate, Peter Goldman. He was also decisive in grasping opportunities. The Daily Mail told him on the eve of the election that its opinion poll would show the Liberals narrowly ahead; he bought 9,000 copies and had them distributed to commuters at all the railway stations in the constituency. He once told me that he had exceeded the legal spending limit at least threefold!

Chitnis became training officer, then press officer, and in 1966 chief executive. But the election of Jeremy Thorpe as party leader marked the beginning of the end of his involvement at the heart of the organisation. He was involved in a vain attempt to stop Thorpe, believing he had little intellectual depth and a tendency to interfere in party affairs without authority. Chitnis's position as head of the party's organisation became increasingly uncomfortable. The party failed to follow his advice that cuts were required, and in October 1969 he resigned.

Chitnis was snapped up by the Joseph Rowntree Social Service Trust (now the Joseph Rowntree Reform Trust) in York as its first professional head. It was an ideal appointment which enabled him to influence public policy without interminable party debates.

He has been described as "self-effacing" but this was not the case. A private person, yes, but always happy to be known as the author of a particular policy or tactic. His marriage in 1964 to Anne Brand, an employee at Liberal headquarters, came out of the blue but delighted colleagues and friends. Their son Simon, born in 1966, was bright and intelligent; it was a huge blow when he developed a brain tumour. He died in 1974.

Chitnis built on the Trust's record by making it more proactive, and often controversial. It put its efforts into peacemaking in Northern Ireland and established relations with liberation movements in southern Africa to assist them to provide administration and services in the areas they had liberated. This latter work was the cause of a bomb arriving at the Trust's York office. Fortunately it didn't go off. He was also instrumental in the introduction of the so-called "chocolate soldiers", whereby bright young assistants were attached to parliamentarians. The scheme was later taken over by the government. Being conscious that many radical groups needed but couldn't afford a London base, he persuaded the Trust to buy a large building in Poland Street in Soho to provide space for a host of worthy groups.

Chitnis joined the Community Relations Commission and the BBC Asian Programme Advice Committee. When he was made a peer in 1977 these appointments enabled him to claim that it was for services to race relations and to sit on the cross benches, even though the peerage was part of the Liberal allocation. In the Lords he defended human rights and liberal immigration policies and was an outspoken opponent of authoritarian regimes that manipulated elections. He monitored elections in El Salvador, Nicaragua and Guatemala, and tried to go to Guyana, only to be refused a visa. He also monitored the Rhodesian election of 1979; other bodies gave it a favourable judgement but he called it "a gigantic confidence trick."

He had let his Liberal membership lapse in 1969 but when Jeremy Thorpe was forced to resign he was instrumental in persuading Jo Grimond briefly to become leader again until a successor could be elected. When David Steel was elected, Chitnis became one of his advisers, particularly assisting with his election tours. He also advised Steel during the Lib-Lab Pact of 1977-78 and during the negotiations that led to the Liberal-SDP Alliance in 1981.

He retired from the Rowntree Trust in 1988 and moved to Provence with Anne, growing olives and attending daily mass. He took formal leave of absence from the Lords and disappointed friends and colleagues by virtually cutting himself off, and was sadly missed over the past 25 years.

Pratap Chidamber Chitnis, politician: born London 1 May 1936; cr. 1977 life peer; married 1964 Anne Brand (one son, deceased); died 12 July 2013.