ultimate secret stock weapon
If you make any sort of a roast it's wasteful NOT to make stock, but I would never ever go on the sort of culinary odyssey that some cookbooks recommend you ("buy 1 cwt. of bones and a calf's head and trotters, roast them in the oven, boil on the hob for 8 hours with 16 aromatic herbs and veggies..." who the hell has time?) And when I do make stock from the leftovers of roasts it tends to come out yummy, but a bit weaker and cloudier than I think it should. Fine for a risotto or a soup base though - just not a sort of shimmery clear consomme.
but you don't need to go the way of the Evil Cube either. Best fake stock in the universe is a thing called "Taste of...." by Knorr, I think, which is a viscous liquid wot comes in a bottle. They sell it in big Sainsburys', dont know about other places. Comes in chicken, beef, fish and veg versions. The beef is a bit over-butch but the chicken is FAB - it's probably full of processed chicken fat but it really does not compare to any other substitute.
[no I am not getting any viral marketing payments from Knorr]