Karolina hears Handel on Brook Street

Discretion, with Karolina, is temperament rather than instruction. She is 174 cm and slim, with long black hair worn sleek, and her brown eyes reveal nothing until she allows them to. Cressida has never once heard her raise her voice. Her dress is minimal and exact: a column of black, a single silver cuff, a coat cut so well it needs nothing added. People notice her arrive. They rarely notice anything else about her until she speaks.

When she does, it is usually funny, a dry wit that arrives sideways in the middle of a perfectly serious sentence. Poised, precise, in her late twenties, she speaks English without hurry. The piano has been with her since childhood, and opera followed naturally: she knows the plots, the celebrated recordings and which arias are worth three hours of waiting. On free afternoons she walks the city looking up, reading cornices and fanlights the way other people read shop signs.

Her favourite small pilgrimage in Mayfair is Handel Hendrix House on Brook Street, where Handel wrote Messiah and where, in the rooms next door, Jimi Hendrix lived in 1968. She finds the pairing irresistible. Claridge's is a short walk on, for a drink, and on the way she will show you three doorways you have passed a hundred times without seeing. She never hurries a walk, even in the rain.

She lives in Covent Garden. Weeknights suit her best, and opera evenings want a few days' notice so the seats can be found. Mayfair is where she meets most guests; Cressida confirms her through booking.