What relevance does that have? How could an examination of the loco at Tyseley tell you how the loco performed over the S&C (and many other routes) in the 80's and 90's? I'm just saying what I, and many others, witnessed during that period and that was that Scotsman was a perfectly capable mainline performer with a single chimney. I'm not arguing that it's not a better performer in double chimney guise. All I'm saying is that the NRM could take it back to single chimney form (if they wanted for aesthetic / marketing purposes) and it would still be a perfectly capable mainline performer. Anyone old enough to have seen it running in single chimney form knows this to be the case. We've seen it first hand. Perhaps Tyseley's judgment was clouded by their experience with the Castle's where Nunney has had a fair few problems out on the mainline, while Earl of Mount Edgcumbe has been a revelation? If I thought of Scotsman in those terms, I'd be recommending a double chimney. But, an A3 is not a Castle.