PICNIC SPOT: Green Park or St James's Park
SHOP: Fortnum & Mason
A stone's throw from both parks, Fortnum's is synonymous with the posh picnic hamper, but you don't have to spend a fortune on its pre-packed extravaganzas. Instead, pick your own selection from the food hall. It stocks just about everything you could want, from hand-sliced Wiltshire ham (£6.50) and melt-in-the-mouth individual goat's cheeses (£4.20) to a wild boar salami for £30.
181 Piccadilly, W1 (020 7734 8040, fortnumandmason.com)
PICNIC SPOT: Regent's Park
SHOP: Villandry
Regent's Park is one of the prettiest in the capital, and you can even take in a trip to the zoo if you are stuck for entertainment. At Villandry, there's a takeaway counter full of seasonal cooked food, like ham and mozzarella calzone and Thai fish cakes, or just go for a simple baguette (£2) and some Brie de Meaux (£1.66 for 100g) on your way to your picnic spot.
170 Great Portland Street, W1 (020 7631 3131, villandry.com)