<<An MoD spokesman said two Royal Air Force Typhoon aircraft had been authorised to go supersonic after a small civilian helicopter had emitted an emergency signal.>>
Incredible.... and ludicrous. God save us from the RAF.
Hindsight is a wonderful thing, but presumably an unknown aircraft squawked a distress code that elicited concern, and wouldn't respond to ATC. The fact it turned out to be a 'small helicopter that transmitted on the wrong frequency' is all good, but those facts presumably wouldn't have been in the possession of the person who, IMHO, not unreasonably made the decision to authorise a supersonic transit.