Dame Jilly died in October at the age of 88 after sustaining a fatal head injury during a fall at her Gloucestershire home.
Following her death, the Queen paid tribute, describing her as a “legend” and a “wonderfully witty and compassionate friend to me and so many”.
The pair were long-standing friends, and the author based her fictional seducer and showjumping lothario Rupert Campbell-Black partly on the Queen’s ex-husband Andrew Parker Bowles.
Speaking with Dame Jilly’s son, Felix Cooper, and daughter Emily Tarrant on set, the Queen expressed her sadness.
“She was such a big part of my life for such a long time. We all miss her so much.” she said.
