Peggy Jay was the undisputed “Queen of Hampstead” (as the billboards proclaimed when she died.) So her sendoff had to be royal in style. As her family said, “Why should the Kray Brothers have all the best funerals?” Yesterday they injected some East End pizazz into NW3, on what would have been Dame Peggy’s 95th birthday.

The Jay clan, headed now by her eldest son Sir Peter Jay, our former Ambassador in Washington, gathered at the last of her nine successive Hampstead homes, to process up the high street, halting the traffic (of which she would certainly have approved) to the church in the heart of the London hill village which she fiercely protected from the depredations of property sharks and fast food joints.

It is not often that he order of service for a funeral shows the deceased raising a clenched fist menacingly at the camera, captioned “Fight the good fight” – but it was a characteristic pose. Armed with pliers and hammer Peggy Jay would tear down estate agents’ boards – thanks to her they are no longer allowed to put up their boards in the village – and once dashed out in her dressing-gown to stop Camden Council chopping down a tree. (Local residents who longed to see the the tree felled, to alleviate the sepulchral gloom of their houses, were not, she declared, fit to live there.)

The procession passed the small discreet branch of McDonald’s, which arrived in spite of her “Burger off” campaign. Heading the throng of 120 were her industrialist son Martin, and sisters, Helen and Catherine, now chic matrons of 62 but more famous as the Jay Twins who wowed the media in the 1960s as Sussex University pioneers in their boots and mini-skirts, plus all 17 of her grandchildren. Several great-grandchildren followed in their prams.

And there were Peter and Virginia Bottomley, former Tory ministers. “Peter only married me because he thought I was going to turn out like my aunt Peggy,” Baroness Bottomley said. “She was my inspiration and mentor. It didn’t matter that I worked for Margaret Thatcher. She could show you how to change the world.”

Levertons the funeral directors were unfazed when the Jays proposed a funeral procession. They had organised the Queen Mother’s funeral, and Princess Diana’s marathon procession up the motorway.

There were also her former daughter-in-law Baroness Jay, and Ferdinand Mount, whose mother Julia was Peggy’s best friend at Oxford, several writers, poets and academics and many women who were inspired by her example – Esther Rantzen of Childline, Marjorie Wallace of SANE, Nicola Beauman who saved Hampstead’s Library, and Helen Marcus who succeeded her in the role of preserving the Heath and Old Hampstead.

Peggy, nee Garnett, was born into a family of radical non-Conformists, bred to privilege, public service and social reform. Her father ran the League of Nations; her grandfather helped found the London County Council. Next door to the Garnetts in Well Walk, Hampstead, lived the Jays: she marked down Douglas, Fellow of All Souls, as the future father of her children. He coached her into Oxford, but in her second year at Somerville she left, at 20, impatient to marry.

Douglas had told her he was opposed to monogamy and he was incorrigibly true to his word. Forty years on, after their divorce, accustomed to public-spirited works (she was the youngest GLC councillor in 1938), she turned her armoury of indignation on anyone daft enough to want to change Hampstead, chairing the Heath and Hampstead Society for 22 years. Having fought so many public causes for poor families and sick and disturbed children, she was “a tigress on behalf of her own children, carrying this to sometimes embarrassing lengths,” as Peter Jay illustrated in his eulogy. When he was in the Navy at 19, and caught German measles in Hamburg (“yes, really”) this might have hampered his promotion to midshipman, had not Peggy had a word with “uncle John’s neighbour, the First Sea Lord.” She was unabashed about using contacts to further her family’s progress, and a stranger to the culinary arts, regarding her fridge (said a granddaughter) as an extra filing cabinet, and never realised that a chicken had to be unwrapped before roasting. Nagging, cajoling, bribing (“50p if you brush your hair”) she was the ultimate matriarch. And in her last days, having defected to the Lib Dems but re-joined Labour because she admired Gordon Brown (Tony Blair “smiled too much” for her), she was still “dissecting the private agonies of the Labour Party”. Her ashes will be scattered on the Isle of Wight, scene of her family’s sailing holidays, where she could be seen, in her eighties, rowing out to sea in a tiny dinghy not far from where Nelson boarded the Victory for the last time.