'A' beacon

I've noticed this beacon over the last few days, usually making the trip in the morning, about 9-10am UK time. Every 10 minutes, it broadcasts 'A' .-
Which of course is intriguing.
I have thoughts of a tiny beacon, battery and small solar panel tucked away somewhere with a wire antenna. Just enough juice to send out it's short identifier...
Of course it could just be a malfunctioning beacon, but that's not quite so romantic...