Another of Elisabeth Luard's books. The Princess and the Pheasant, has a soup called Ajo Blanco:

3oz blanched almonds
4 cloves garlic
2 tbs olive oil
2 pints cold water
salt
1 tbs white wine vinegar
handful of white grapes

Liquidise oil, garlic, almonds and 1pt water. Add the other pint of water. Season with salt and vinegar. Leave to infuse in the fridge for an hour. Peel & pip grapes. Before serving, add grapes and a piece of ice per serving.
(I've shortened her language a bit)