I've done many a leg of lamb in front of a fire without any need to butterfly it by suspending it just to one side of the fire and turning it every 15 minutes for about 2.5 - 3 hours depending on the size of lamb.
Tasted absolutely delicious![Big Grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Tasted absolutely delicious