Full story:
http://news.bbc.co.uk/1/hi/england/west_yorkshire/7599110.stm

*U.K. pavement = U.S. sidewalk

That's incredible Paul. What a horrible way to die. I'm still curious how the "pavement" could have been energized and if so, wouldn't the horse and the rider have been at the same potential? Something doesn't sound right here.

Ed,
By the sounds of it, there was a damaged power cable below the ground surface, what can happen when cables get damaged is a voltage gradient "pool" is set up on the ground above and this radiates outwards from the centre of the faulted part of the cable.

Now, if 1 of a horses 4 legs are touching one part of the "pool" and another leg is touching another part of the "pool", a potential difference then exists between these two legs.

Unfortunately, this cable had not sufficiently faulted to blow any protective equipment.

The reason the rider was not electrocuted as well, is because the rider was "insulated" from the horse by clothing and the saddle.

{I hope this explanation makes sense}

It does sound like a damaged cable, although unfortunately we often seem to read the initial report in the media on something like this but never get to hear the results of the investigation.

This reminded me of all those energized-manhole stories from Con-Ed in New York City over the last couple of years.