Cook the pearl barley in a pan of boiling water for about 20 minutes, until soft. Drain and put to one side.
Preheat the oven to 180C/350F/Gas 4.
Rinse the poussin or guinea fowls under cold running water and pat dry thoroughly.
For the stuffing, heat the olive oil in a heavy frying pan and cook the shallot and sour cherries for a few minutes until the cherries are plump and juicy.
Add the cooked pearl barley and continue cooking for 2-3 minutes.
Add the toasted walnuts, parsley, pomegranate molasses and lemon juice and zest. Stir well and leave to cool.
Once the stuffing has cooled, use it to stuff the cavities of the birds, dividing it evenly between the two. Don't worry if the stuffing overspills.
Smear the outside of the birds with butter and sprinkle with salt and freshly ground black pepper.
Place the birds in a large roasting tray and add the wine and pomegranate juice. Roast for 30-35 minutes or until cooked through, basting at regular intervals.
When the poussin or guinea fowl are cooked, remove from the oven and leave to rest for 10 minutes. Carve and serve with the stuffing.