The artist and left wing political activist was born in Berlin, Germany, where her father Sir Alan Gardiner, the Egyptologist, was working at the time. Her education was undertaken at the Frobel School, Hammersmith, Bedales in Yorkshire, and latterly at Newnham College, Cambridge. She was able to devote her life to politics and the arts, thanks to the family wealth.

Gardiner was a friend of Barbara HEPWORTH, Ben NICHOLSON and many other artists whom she actively supported in their modernist agendas for art. Though she maintained a home in Hampstead most of her life, she visited often in Cornwall, especially during WWII (1939-45). She also spent time often in her favourite retreat on Rousay, Orkney. In 1979 she was the founder of the Pier Art Gallery in Stromness, and it was to the people of Orkney that she gave 67 works of art, including Curved Form (Trevalgan), Barbara Hepworth's first entirely bronze work. The latter sculpture now adorns the pier at Stromness.