Baroness Masham of Ilton, Paralympian, campaigner, horsewoman, and the longest ever serving female member of the House of Lords, has died aged 87.

An independent crossbencher, Susan Lilian Primrose Cunliffe-Lister was made a life peer in 1970, and was a passionate advocate for disability rights.

Announcing her death, the Spinal Injuries Association (SIA), which she founded in 1974, said: “We are extremely sad to announce that our founder and life-long president, Baroness Sue Masham of Ilton, passed away peacefully at Northallerton hospital on Sunday.

“It goes without saying that everybody at SIA is devastated to have lost our greatest champion.

“Forty nine years ago, in 1974, she founded SIA and is the reason we have been able to champion, fight, serve and support thousands of spinal cord injured people ever since. Our condolences go to her family at this sad time.”

The British Paralympic Association described Baroness Masham as a “pioneering athlete”. She got involved in disability sport after meeting the founder of the Paralympic movement, Ludwig Guttmann, at Stoke Mandeville hospital in 1958, where she was being treated for a spinal injury suffered in a horse-riding accident at a point-to-point event.

Describing the fall in a 1993 interview, she recalled: “A warble fly pressed on the horse’s spinal cord, he gave an extra jump and we came down together. If I had come off I would have been all right.

“I was at the spinal unit in Stoke Mandeville and saw people worse off than myself. I thought I was lucky to be alive.”

Baroness Masham

Baroness Masham

After that meeting with Ludwig Guttmann, Baroness Masham became one of Great Britain’s first ever Paralympic medallists, winning three at the inaugural Paralympic Games in Rome in 1960. She claimed further Paralympic success at Tokyo 1964 and Tel Aviv 1968, where she won medals in table tennis and swimming.

Last year she was presented with an exact replica of the swimming gold medal she lost during the Rome Games at a special ceremony hosted by the British Paralympic Association.

Its chairman Nick Webborn said: “She was an exemplar of a purposeful life well-lived. Through her life she was a champion of disability rights as well as a Paralympic champion. Last summer we were delighted to be able to present her with a replica of the medal she lost at the very first Paralympics in Rome and she enchanted us with stories of those early days in the Paralympic movement. A true lady who will be missed by many. Our heartfelt condolences to all her family."

Susan Cunliffe-Lister, Dowager Countess of Swinton, DSG, DL, Baroness Masham of Ilton, during the launch of a report by the charity which supports families of children on long-term ventilation at Portcullis House, central London.

Susan Cunliffe-Lister, Dowager Countess of Swinton, DSG, DL, Baroness Masham of Ilton, during the launch of a report by the charity which supports families of children on long-term ventilation at Portcullis House, central London.

Sue Sinclair, as she was before her marriage, was the daughter of a Scots baronet. Aged 22, she was working as a riding instructor and engaged to David Cunliffe-Lister when she was paralysed.

They married in 1959, and a wedding gift of a single Highland pony called Corrie marked the start of a remarkable hobby for Baroness Masham, who built up an impressive stable, winning awards at shows across the country. Her affinity with Highland ponies sprang from her upbringing in Caithness, and her love of animals never waned. She campaigned on animal welfare, and many other issues, but it was her work for the disabled which saw her given a life peerage, and title Baroness Masham of Ilton, in February 1970. Aged 34, she was the youngest ever life peer.

She had wanted to take a Scottish title, but was told by the Garter King of Arms – the head of heraldry – that it would be difficult because English and Scottish titles are managed separately.

Baroness Masham was patron of many charities, including Chopsticks, in Northallerton, and Yatton House, in Great Ayton, and worked tirelessly on health and social causes.

Speaking in 1993, she described one of her main concerns as AIDS. “It is a field some people shy away from,” she said. “When people are ill, whatever the cause, they need looking after.” She worked closely with Princess Diana on a number of projects, and added: “She has been very good and caring in the field I work in.”

The family seat was Swinton Castle, near Masham, but the couple lived nearby in a modern four-bedroomed bungalow with their two children. The castle was later sold and turned into a conference centre, before being bought back by the Cunliffe-Lister family. It is now a luxury spa and hotel.

Her husband David died in 2006 aged 69 after many years of ill health.