Put the pearl barley into a saucepan and add enough water to cover generously. Add the stock cubes, bring to the boil, then reduce the heat and simmer for 1 1/2 hours until tender, topping up the water if necessary.
Melt the butter in a large frying pan or wok and gently saute the saffron, onion, and pepper for 5 minutes. Add the chorizo and bacon, and fry on a higher heat for a further 5 minutes.
Add the garlic, most of the thyme leaves, paprika, wine, tomatoes, and peas. Bring to the boil, then simmer for 5 minutes. Stir in the prawns and simmer for 2 minutes to heat them through.
Drain the pearl barley thoroughly and stir it into the other ingredients, making sure it's piping hot. Serve immediately, garnished with a few thyme sprigs.