12v Aux Socket in Rear Compartment

[Irvin Berlingo]

Whilst I'm enjoying Irvin, amongst various things I'm surprised at the lack of for a mid-trim model is the lack of a rear 12v aux power socket; thought that was fairly standard now for hatchback/estate vehicles. My last two vehicles both had them and they were really useful.
I've looked through the various threads on here regarding retro-fitting a socket, although I'd probably mount in the pocket/recess on the rear driver's side for tidiness rather than stuck on the top by the speaker. However the question is always of wiring ...Is there any already in place ? Which wires carry a suitable live feed ? etc etc I find it hard to believe that Citroen/Renault would have a separate wiring loom for every variation of every model, usually the wiring loom is standard as that is simpler and cheaper for production, but only having certain options plugged in ??  
Since the threads posted has anyone found any more info/diagrams on the wiring, available sockets or any good working solutions ?
Need a rear socket for cooling solutions for the doggos, amongst other things 

[cancunia]

According to the diagrams, the wiring is already there, but my experience was that it's not already there. The only way to be sure is to remove the trim panel.

[Irvin Berlingo]

Thanks for the reply 
That seems to be the case sadly. Hopefully I'll have some downtime this week to have a faff around and see what I can dig up.
I remember having a Peugeot in the past that had various electricals not fitted but the wiring/sockets were there, just fairly tucked away .... hopefully it will be the same ?!

[deejay_xb]

the wiring should be tucked in the right boot compartment, you need to take off the large trim panel

[Irvin Berlingo]

Had a few minutes to pull the rear side trim panels off.
Found no obvious connectors on the Driver's side. Found green and green/yellow wires, as part of the taped loom, mentioned in another thread that connected to their fitted 12v socket but again no obvious connector for same.
Found 3 connectors on the passenger side as pic'd. Green multi connector with 1 thin wire, orange multi connector with various wires and one chunky red/black connector with a thick white wire, stated elsewhere as a permanent live ? These are trailer connectors ?? If the white is a permanent live (didn't have my meter with me to check) that could well feed an aux power socket ?

[cancunia]

Some searches on the tow bar wiring should come up with more info, but here's a starter.

https://www.berlingoforum.com/thread-18570.html

[Concizat]

Had a few minutes to pull the rear side trim panels off.
Found no obvious connectors on the Driver's side. Found green and green/yellow wires, as part of the taped loom, mentioned in another thread that connected to their fitted 12v socket but again no obvious connector for same.
Found 3 connectors on the passenger side as pic'd. Green multi connector with 1 thin wire, orange multi connector with various wires and one chunky red/black connector with a thick white wire, stated elsewhere as a permanent live ? These are trailer connectors ?? If the white is a permanent live (didn't have my meter with me to check) that could well feed an aux power socket ?

That white cable is the 12v. supply for the trailer lighting. It may or may not be live. If not you need to fit a 35 amp maxi fuse in the fuse board in the engine compartment. If you search for "trailer wiring" here you will find all the info you need. 
I have just fitted trailer lighting to mine and also took a link from there to install a 12v socket at the rear with a separate 15 amp fuse.