Not 100% correct electrical advice.

[zappa]

If you intend to run the spur from an existing socket, firstly check whether the socket is suitable to supply a spur.

SWITCH OFF ELECTRICITY AT THE MAINS

Turn off the main supply on the consumer unit and ensure the socket you plan to use is dead. Remove the cover to the socket and inspect the wires going into the socket.

If there is one cable going to the socket, then that socket is already on a spur and is therefore unsuitable. If the socket has three cables going to it then it is already supplying a spur circuit and so again again is unsuitable. Once a suitable socket has been found, you can close it up for the time being and restore electricity until you are ready to connect the new socket

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So if it only has 2 x cables in then it's ok to chuck another one in as a "spur"? What if it's already a spur with a spur off it?? Surely the ring integrity needs to be established properly first. This can't be done by just simply having a quick look inside.

 

[sparkyspike]

This is a very brief description of fitting a spur. As this is a diy site, it doesn't go into other checks you need to make. This would take pages and pages. There are always going to be problems on a site which is showing diyers how to do electrics, when in many cases you need a spark to do the job. I agree with you that you need to find out exactly what is going on in the wiring before you start, but you need at least an ohmmeter etc. plus some knowledge. And it brings up the age old subject of runing spurs off ring mains which is acceptable but controversial.