Just been channel-hopping while I'm waiting for the wife and came across an episode of DIY SOS. Billy the electrician was complaining that someone had wired up some sockets in the kitchen by running the cable left-to-right instead of up-and-down.
I thought you could run cable both vertically and horizontally, as long as it is a straight run to an obvious socket/switch/whatever, eg, come down from the ceiling to a socket, then say out a metre to the right for another socket, and then take the return leg back to the first socket box and back up the chase to the ceiling again?