Question Author
GG . . . I concur with your answer as to the name of the canal.
It was the date of the arrival of the S&GR railway stated as "1845" and the length of that particular tunnel at "2,800 yds" that took me more time to research/confirm.
The posting does suggest that Tilly may be thinking of taking up the challenge, going forward - if she does - let's hope she gets as much enjoyment out of it as we do? Who knows, if she has entered this week and wins, she can report if the Grand Excelsior in Sorrento has changed much since her last visit!