For all the "holier than thou's"...relax. If you really thought it was a secret (which it wasn't), it's not any more. BBC quoting MOD spokesman and helicopter instructor:
Mr Tinworth said there were four Typhoons on alert, 24 hours a day, 365 days a year.
"The only time anyone hears about it is when it's over land and when there's noise made - which happened yesterday.
"Pilots need authorisation to go supersonic because it makes noise and upsets people," he said.
This sequence of events was backed up by a helicopter instructor, who did not wish to be named.
He said: "The transponder is a box on the dashboard and it just identifies which green blip you are on the screen for air traffic control.
"The number that you put in the transponder if you're just flying around is 7000.
"But if you've been hijacked, you put in 7500.
"So it's possible he might have entered the hijack code instead - and in the current climate, that well might trigger Typhoons.
Personally, I think that's exactly what happened.