I wish I could say that I had solved it but... I have two answers in my head at the moment!
I was always taught that the Tyne was one of the fastest rivers (and certainly satisfies the question of length).
Then I flicked through some old research notes and found that Glamis was the name of a sabotage plan used by the SOE. Certainly, the late Queen Mother’s brother was head of the SOE for a time, but beyond that, I’m lost. Neither the Tay nor the Isla are 73 miles long and the 13,000 thing has me stumped.
If it is that neck of the woods, then it’s highly embarrassing. I lived in Fife and Tayside for 20 years...!