My Pop was a fireman on the LMS 1938 all through the war until 1947 and had fired most types of loco albeit some in the yard only. He once fired the Turbomotive down from Camden to Euston and told me that she was a good engine when working right, but was a bit of a hungry beast coalwise. He was once sidelined somewhere when she came speeding past and said she made a sound rather like a jet plane. I'd love to have seen that.