Smitty wrote:...motto of story
there is always someone bigger and stronger than you.....

Like the aircraft-carrier-vs-lighthouse story...
...this one's implausible on a number of levels. First, as anyone who's been to the GP and seen the de-rigeur Hornet low-level display would probably agree, with a jet warplane, you hear it well before you see it. By the time these cops saw the approaching dot, they would've known there was something turbine-powered and angry about.
Then, 300mph works out to five miles a minute, ie. a mile every 12 seconds. What's the range of a police hairdryer?
Further, the electronic warfare suites on board combat aircraft typically include vast libraries of radar signatures... frequency band, frequency sweep range and duration, pulse duration, rate and profile and so on, and the type of radar they correspond to. The system would've gone "Ah, it's a police hairdryer" and told the backseater in the Tornado (not the pilot, as the story claims; at low level, he'd've been too busy either flying the plane himself or watching that the terrain-following system wasn't about to fly the plane into the aforementioned terrain) as much; it wouldn't've been the other way around, with the crewbloke recognising the radar signal by eye.
Further still, combat aircraft ordnance being expensive and scarce once an aircraft actually takes off carrying some means air forces tend to be loath to see it released unnecessarily by, say, a spooked weapons-control computer. Combat aircraft don't operate in the sort of fire-at-will mode described here, with a trigger-happy automated system running in the background the crew have to second-guess and calm down on occasion. There is such as thing as automated weapons release, but that's a multi-step process programmed in and manually initiated by the crew for the attack on a known target; the computers work out at what speed, angle and altitude to bring in the aircraft from and when to let go of the ordnance.
Finally, the story requires the Tornado to have been flying through unrestricted civilian airspace with its weapons and electronic warfare systems hot, and carrying live, armed ordnance. Forgetting for a moment that the RAF, like most of NATO, conducts its live-fire training in the US (unlike in continental Europe, there's plenty of desert to bomb there), so the aircraft would've been very unlikely to have been carrying live weapons in the first place, that's about as gross an act of operational negligence as you can get in military aviation, short of actually going "oops!" and dropping a cluster bomb onto a Maccas. Had this aircrew actually done this, when they got back to base, their commanding officer would've been on the phone to the Navy, arranging to have them keel-hauled.
On top of everything else, "laconic" means "terse" or "curt". A laconic reply from the RAF to the chief copper would not have included words like "furthermore".