Catherine Sedley, Countess of Dorchester, Countess of Portmore (21 December 1657 – 26 October 1717), daughter of Sir Charles Sedley, 5th Baronet, was the mistress of King James VII and II both before and after he came to the thrones. Catherine was not noted for beauty but for her wittiness and sharp tongue.

'Good God, who would have thought that we three whores should have met here!'

The Countess of Dorchester , mistress of James Il on encountering the Duchess of Portsmouth,mistress of Charles II, and the Countess of Orkney, mistress of William III, at the coronation of George I, October 20, 1714

• from Wikipedia: Catherine Sedley, Countess of Dorchester

Catherine was the only daughter of Restoration hellrake and poet Sir Charles Sedley. She grew up "notoriously plain." While her father roistered around England, her mother spiraled into insanity until she entered a Psychiatric hospital in Catherine's early teens. At this low point in her life, Sir Charles consoled his daughter by introducing a common-law wife into the family and ejecting Catherine from the house.

She landed a job with Italian princess Mary of Modena, who had just married James, Duke of York, heir to the British throne. This eventually led to an affair with him. She was bewildered at having been chosen by James."It cannot be my beauty for he must see I have none," she remarked incredulously. "And it cannot be my wit, for he has not enough to know that I have any."

• from the Scandalous Women blog spot

In August of 1696, Catherine, at the age of thirty-eight, married a one-eyed Scot named Sir David Colyear, afterwards the first Earl of Portmore. He was an officer in William III's army and highly respected. By her husband, Lady Dorchester gave birth to two sons, and by all accounts the marriage was a happy one. When her sons were sent off to school, she told them, "If anybody call either of you a son a whore, you must bear it; for you are so: but if they call you bastards, fight till you die; for you are an honest man's sons."

Lady Dorchester died at Bath on October 26, 1717 at the age of 60 of unknown causes. While her former lover, James II came to regret his prolifigacy in his old age. "I abhor and detest myself for having lived for so many years in a perpetual course of sin," apparently she had no such regrets. She leaves behind a legacy of priceless bon mots. At the coronation of George I, when the Archbishop of Canterbury formally asked the congregation for the people's consent to the King's crowning, the Countess was heard to say loud and clear, "Does the old fool think that anybody will say no to his question when there are so many drawn swords?" (Charles and Camilla, Brandreth page. 21).

Catherine gave birth to several children while James II's mistress, but only a daughter survived. The daughter Catherine, although acknowledged by James, in all probability was the daughter of Colonel James Grahame, a witty and fashionable hanger-on at court and the King's Keeper of the Privy Purse. Apparently Catherine felt no need to confine her favors to just the one man. When her daughter began to give herself airs, Catherine told her, "You need not be so vain, daughter, you are not the King's child, but old Grahame's."