This is Lady Joanna. Robert's mother, the Dowager Duchess of Cantin.
In THE DUKE'S DIVORCE, Lady Joanna tries to persuade Robert he needs to remain married to Fiona. He doesn't want to hear it. But when his friends tell him, "Mother knows best" he wonders if they are all in cahoots.
I like Lady Joanna. She's very kind and does offer up some very sage wisdom.