A Stuart 504 boiler for restoration - the largest of their 500 range, 2 3/4 inch diameter barrel with a 60psi working pressure.
Missing burner, chimney and safety valve, although since taking the pictures we've found the Stuart 0-80psi pressure gauge. Side plates want painting, the chimney wouldn't be too difficult to make and most 504s have, over the years, had their original spirit burners replaced with a modern ceramic gas burner anyway - it's a much more controllable way of firing the boiler.