The Mysterious Marquis — Eileen Ainsworth Ramsay

Returned from the Valley of the Kings, Elizabeth Ridgeway enjoys a break from collating her archaeologist papa's notes by walking in the lovely woods around her Perthshire home. There she discovers a small boy who has fallen into a stream. Since he appears to fear to return to his own home, the secluded Kirkdale Manor, Elizabeth takes him home and discovers that Rowan is motherless and that his father, the Marquis of Kirkdale, has abandoned him to an elderly nurse and a tutor who drinks. Elizabeth decides that she abhors men like the marquis and sets herself to making life more fun for the child.
Meanwhile in London, the rich, spoiled Alicia has fallen madly in love with the unapproachable marquis. Her father sends his indigent nephew to Scotland to uncover the history of Lord Kirkdale from his estranged father, the stern and forbidding Duke of Strathelvan. At the same time the marquis, deciding that he must rectify the Scottish situation, returns to his Scottish seat just after a snowfall. He is intrigued and amused when a small boy and a red-headed woman - with shapely legs - slide, on a tray, almost under his stallion's iron-shod hooves.
Soon the marquis finds himself, his house and his life being rearranged, his relationship with his father and his son repaired, not to mention his son being kidnapped at the British Museum; and then there's the small matter of a new-fangled idea called The Christmas Tree, complete with lighted candles, in his Drawing Room. It's more than a proud man can bear, or is it?