Replacing a junction box - single socket in hallway

[Delidee]

I hope you can help me, I am normally very happy to tackle any jobs at home but having been brought up by an electrocal engineer I know better than to mess about with the silent killer.

At present I have a single socket in my upstairs hallway which is coming away from the wall ie. cannot be used as when removing plug, socket slightly protruding. I thought it would be no problem to replace this with a double socket (had done this before), only to find when I removed faceplate that this is a junction box with multiple wires connected, And here was me expecting the three standard ones I am familiar with

I wondered if it is possible to replace this socket with a double socket, even more importantly is it possible to be done myself OR a job for a professional only?

Any guidance anyone can give me would be much appreciated. Thank you.

 

[PrenticeBoyofDerry]

Hello Delidee and welcome,
How many cables are in the socket back box?
I assume all these cables are actually terminated to the socket plate or are some terminated into connections external to the socket plate?
It could well be a spurred socket, which will not only be part of either a ring or radial circuit but supply an addition socket elsewhere.
I would expect no more than 3 sets of cables terminated to the socket plate, these being 3 reds, three, blacks and three bare copper (which should be sleeved) or green/yellow. cables.
It is possible for single socket to replaced by a double outlet.
New colours would be
brown for reds (phase)
blues for blacks (neutral)
Sleeved bare copper (CPC/earth) same colour if not green only.