Under the pavements of Maida Vale, there is a basement flat unlike any other – two quite shabby small white rooms, full of rows of couture ballgowns; explosions of tulle and chiffon, bodices of exquisite lace, jewels and gold braid.

Mock military jackets line one rail, worn by Madonna on her Madame X tour. On a mannequin sits an Marie Antoinette-style waterfall dress of grey silk duchess satin and black tulle. That dress was made for the actress Courtney Love, wife of the late Nirvana frontman Kurt Cobain, who wore it to the National Portrait Gallery’s fundraising Gala in March.