Put the chickpeas, spring onions, herbs, egg yolk, piri piri sauce, Worcestershire sauce, mayonnaise and 50 g (2 oz) of the breadcrumbs in a food processor and process briefly. Add the crab meat and pulse quickly to combine, adding more breadcrumbs if the mixture is too wet.
Transfer the mixture to a bowl and form it into 4 large or 8 small patties. Press them into the remaining breadcrumbs until well coated.
Heat the oil in a large frying pan and fry the crab cakes for about 5 minutes, turning carefully once, until crisp and golden. Drain on kitchen paper and serve immediately with rocket leaves and a dollop of aïoli.