So - heard back from the Blacksmiths today, and they have done my grill and charcoal basket from SS:
As expected, they used the perforated metal that is more common here, but the first thing that struck me is that the charcoal basket which is 8" high is 18" wide! I think I got this slightly wrong as this is going to hold kilos of lump!
What diameter is generally thought to be right? I know 8" was suggested as the usual height (and I will be adding bolt legs to this and getting it into an ash pan) but I think I have exaggerated on the diameter. Even so - one solution I thought of is to put a couple of fire-bricks in the middle, stood on their ends, that would fill the space and reflect some heat.