Mix together the crushed garlic, thyme, oregano, lemon juice and olive oil.
Cut the spine out of each poussin with poultry shears or a large knife and flatten each bird.
Insert wooden skewers across each poussin to keep flat. Place in a roasting tray and add the marinade, coating the poussin all over. Cover and place in the fridge overnight.
As soon as the barbecue is hot, break up the bulb of garlic, wrap in tinfoil, place on the grill and cook for 1 hour.
Heat the oven to Gas Mark 4, 180°C, 350°F place the poussin flat on two roasting trays and cook in the oven for 20 minutes, then transfer and cook on the barbecue for 5 minutes, and turn and cook for a further 5 minutes.
This will finish off the cooking and add that delicious barbecue flavour and appearance. To check that they are cooked, insert a knife in the thickest part and juices should run clear, if not return to the barbecue.
Serve, scattered with olives, roasted garlic and basil leaves.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home.