IT is easy to be sceptical about some politicians’ values, but with Robert Maclennan there was never any doubt. He put political purpose – pursuing liberty and equality, seeking to tackle poverty, ignorance and conformity – before party. He abhorred personal attacks and avoided tribalism. He was liberal to his core. He once told me that as a Labour MP he sought to work across the party’s factions, but had “never let the word socialist pass his lips” in describing himself.

Few people have a fundamental influence on you, but Bob did on me. His articulation of liberalism gave form to my political instincts. I was his Commons researcher in the mid-1990s, that heady progressive era of New Labour. Bob was Liberal Democrat President, at the heart of Paddy Ashdown’s efforts to persuade Tony Blair to embrace constitutional reform.

Paddy had closer allies in his party, but put Bob in charge of negotiations with Labour (the Cook-Maclennan talks). From the previous negotiations to merge the Liberals and Social Democrats, Paddy knew that, while Bob was a gentleman in all senses of the word, he possessed steely determination and strategic rigour.

The Labour leadership’s ambivalence about implementing constitutional reform is now forgotten, but Bob helped persuade them to act. He and Robin Cook enjoyed shared purpose, got on well, and collaborated more closely than their respective leaders perhaps realised.

Bob and Paddy, collaborating with Labour reformers, even marched Blair up to the top of the electoral reform hill, persuading him to establish the Jenkins Commission on proportional representation. Sadly, they couldn’t get him over the crest. How different our politics could have been now if they had succeeded.

Bob was born in Glasgow in 1936, and his memories of the war drove his instinct for international partnership and pluralism. A passionate European, in 2012 he was the first person to use the word “Brexit” in parliament, describing it even then as “hideously fearful”.

But that was just the politics. He delighted in art, music and history. Writing the libretto for an opera, Friend of the People, about eighteenth century Scottish reformer Thomas Muir, which was performed by Scottish Opera, invigorated him. In Bob’s company it was impossible to pass even the smallest art gallery or bookshop. Sitting in his house (frequently with a strong gin martini) I’d look up and notice yet another new painting. He took pleasure in his daughter Ruth’s artistic career and his son Adam’s business success.

Bob was a modest man, with little to be modest about. He had a classical education and a reputation as serious and intellectual, but that belied self-deprecating, twinkle-eyed, humour. At a party conference in Glasgow, he once began a speech in Latin. The audience, knowing Bob, erupted with laughter. During that conference I’d hurriedly written and put out a press release in his name, without showing it to him first. A journalist challenged its authenticity as he’d spotted a split infinitive, an error Bob would never have made.

He was also endlessly curious about people. Bob would chat to anyone, seeking their opinions and ideas, from the barista serving him coffee, to former Cabinet ministers. He inspired enduring loyalty; Maggie Harrison, who ran his office, worked with him for decades. Bob and his wife Helen loved entertaining, and were generous hosts in their London and Caithness homes, places full of friendship, colour and interest.

Ten years after I stopped working for Bob, we collaborated again, on a tidal power company with potential for his former Caithness and Sutherland constituency. It ultimately proved fruitless, but reinforced our friendship. By then he was in his 70s, but his work ethic remained extraordinary. A full-time peer, he was constantly buzzing with new ideas for cultural and political projects.

Bob’s was a life bursting with positive purpose, a life of absorbing interests, and a life that enriched those of others.