[1] Maggie's father was taipan of Jardine Matheson, the influential Scottish–Chinese trading company.

[3] Keswick was educated in England and read English at Lady Margaret Hall, Oxford.

She collaborated with her husband on the design of the gardens at Portrack, their family home near Dumfries, Scotland, and on extensive alterations to the house's interior.

Her other garden designs included one inspired by the pastoral poems of John Milton for the Jencks' house in California; a collaboration with the American architect Frank Gehry on the Lewis House at Cleveland, Ohio, where fibre-optics and running water created a highly original landscape; and a garden for the film director Roger Corman.

A bust of Jencks is on display in the Hall of Heroes of the National Wallace Monument in Stirling.