Woman's Satin and Lace Garment
"Harvey Nichols, Knightsbridge, London S W"
Maureen Donnelly, who kindly shared her photographs of this item from her collection, suggests it may be either a lavish dressing gown or morning coat and that it may date from mid-Victorian years. Since lace collars became popular in the 1880s, it could also date from this later period.
The firm of Harvey Nicols grew out of Benjamin Harvey's linen shop, which he founded in 1813, and it combined with a Captain Nichols in 1820. The existing Knightsbridge store opened only in 1880 [company site], but I do not know at what point the firm began to sell women's clothing.