That sounds a brilliant idea Usedtobeblonde thank you, I'll try it. I should have told everyone I've tried the traditional ways of skimming off the fat and using the residue - it works brilliantly with beef etc, but not with lamb (well not for me!) Maybe the ice cubes will take care of that, I'll let you know.
I didn't know Bisto made lamb granules, I've looked on the supermarket shelves and never seen any. I only have one reasonably close supermarket and its not the best so maybe I should travel to a bigger town for my shopping 
You really must try mint gravy JackyB we have mint sauce or jelly separately as well.