Fortnum & Mason
Although F&M was jokingly known as "the Queen's grocer" (time will tell if the nickname will keep pace with the change of monarch) and the impeccably mannered staff still wear traditional tailcoats, its celebrated food hall stocks gifts for all budgets, including irresistibly packaged luxury foods stamped with the gold "By Appointment" crest for under £5. Try the teas, preserves (including the unusual rose-petal jelly), condiments, or Gentleman's Relish (anchovy paste). The store's famous hampers are always a welcome gift.
The gleaming food hall spans two floors and incorporates an opulent cocktail bar, with the rest of the store devoted to upscale housewares, men's and women's accessories and toiletries, a dedicated candle room, and a jewelry department featuring exclusive designs by breakthrough talent. If you start to flag, take a break in the tea salon; or FIELD, which specializes in local ingredients and overlooks the food hall; or the contemporary 45 Jermyn St. restaurant (the three-course set menu is a good value); or head to the indulgent ice-cream parlor, where you can find decadent treats like a banana split or a less-traditional gin-and-tonic float. They've even started distilling their own pink and dry gin on the premises, so visit the third floor for a taste, where you can also book masterclasses and dining experiences at the Food and Drink Studio. There's another branch at St. Pancras International train station.