Torque of the Devil and SARCO, you both have good points.
The police forces provide mutual aid to each other. When a helicopter goes "cross border", it's use will be charged for. I guess they, wrongly, apply that thinking to SAR aircraft.
Torque of the Devil, I do not know the urgency of the lift in question, but imagine it must have been high to warrant that sort of risk. I think the incident happened in Worcestershire; where would the nearest SAR aircraft come from and how soon would it have been on scene? I assume either Valley or Chivenor at alert 15 day time?