Lamb's breast (also called lamb ribs/riblettes in the US) are a very under used cut of lamb. It's cheap, but very fatty, so can be a bugger to cook.
There's all sorts of recipes for braised or boned breast, but not too many for bone-in, roasted. I found this on the web when I was looking for recipes and, being oven roasted, I was all over it.
Slow roasted vegetables