Eh, Shaggy, re-read the first two posts. It's famous as it is claimed to be the first steam locomotive to have exceeded 100mph.
'City of Truro' appears to have at least as strong a claim to that, according to the second post.
'Flying Scotsman' is the Harley Davidson of the loco world - everyone who knows nothing of the subject knows the name, and thinks it represents 'best in class'.
SSD