I am not an electrician but physics/electronics teacher .... having read your question a word of caution in using a 3-neon-plug-in-tester. While 3 neons will indicate that an appliance plugged into a passed socket should work it could give a false sense that all is well.
If you have been decorating it is possible that a nail or similar has penetrated a mains cable and made electical contact (most dangerous case) with the live wire while missing the neutral and earth wires. In such a case you will get 3 neons but you will also get a shock if you touch the nail!
A competent person could check this out when the MAINS IS TURNED OFF by testing for such an electrical connection by an electrical continuity test using a multimeter.
To get an electrical shock you only need to touch the switched-on-live wire and an electrical earth route such as the floor or a wall.
This is another storey version of drilling into a mains cable.
best wishes Nyge C