Cary-Hiroyuki Tagawa - Lieutenant A. J. Shimamura (seasons 1 & 2)

Josh O'Connor (seasons 3–4) and Dominic West (seaons 5-6) - Charles, Prince of Wales

Emerald Fennell (season 4, featured season 3) and Olivia Williams (seasons 5-6) - Camilla Parker Bowles

Claire Foy (seasons 1–2, featured season 4, guest season 5), Olivia Colman (seasons 3–4), and Imelda Staunton (season 5-6) - Queen Elizabeth II

Mary Test (voiced by Brittney Wilson in Seasons 1 and 5, Ashleigh Ball in Seasons 2-4 and 6)

Jaime P. Gomez - Inspector Evan Cortez (seasons 1–5)

Dukey (voiced by Louis Chirillo in Seasons 1-4, Trevor Devall in Seasons 5-6)

Yasmine Bleeth - Inspector Caitlin Cross (seasons 4 & 5)

Serena Scott Thomas - Kelly Bridges (seasons 1 & 2; guest season 3)

Annette O'Toole - Lisa Bridges (seasons 1 & 2; guest seasons 3 & 4)

Jeremy Northam - Anthony Eden (seasons 1–2)

When the Seasons' changes thus confront the mind
What comfort can the Doctrine of Tao give?
It will teach me to watch the days and months fly
Without grieving that Youth slips away;
If the Fleeting World is but a long dream,
It does not matter whether one is young or old.

Vanessa Kirby (seasons 1–2), Helena Bonham Carter (seasons 3–4), and Lesley Manville (seasons 5-6) - Princess Margaret, Countess of Snowdon

Things That Lose by Being Painted
Pinks, cherry blossoms, yellow roses. Men or women who are praised in romances as being beautiful.Things That Gain by Being Painted
Pines. Autumn fields. Mountain villages and paths. Cranes and deer. A very cold winter scene; an unspeakably hot summer scene. (p. 138)