Like a foolish retarded idiot I have chopped into the main ring circuit and completely severed the cable. I was chopping out a socket and cable wasn't exactly where I expected it to be. The cables are buried behind plasterboard and I have cut away the area to expose the offending cable. I know the locost way is chocblocks wrapped in tape but I'd rather not.

Is there a small connector box that someone can recommend that can be perminately buried in the wall???

Wago's in a small box? But the electrician who did some re-wiring on a place I was recently working on used blue insulated connectors, the same as often used on cars. Just crimped them up.Then wrote the certificate.....

I would prefer Wagos or a decent choc block (after all a choc bloc is the same system as used on every socket/switch in the house)

I think Waco's are the preferred way and when I last looked at them supposed to be more reliable long term. But I'm no electrician ....

I think the safest option is to chop the cable out to the nearest socket and place another socket where the damage is. This will mean I will have a bit of a random socket and I will have to chase a metre or so of cable. This is a bolt and braces option and will pass part P.

You need to have access to any threaded connections. If not, the push fit connectors wagos will be fine.

Personally I'd be fitting another socket (never know it might be handy for hovering etc) and joining it with that.

I would suggest using through crimps as the best option if the joint is not accessible? I tell my sparkies only to use a junction box if we can get to it afterwards. But best of all replace the broken leg of the cable, hopefully you can use the broken one as a draw wire.

I believe it has to be maintenance free if not accessible; sparkies will know better than me, but this may well be acceptable

https://www.amazon.co.uk/Ashley-J803-Maintenance-Terminal-Junction/dp/B00BATALJK

The through crimps are what son uses and he is a sparkle or could you not fit a new box at the break

No chance of fitting a socket at the break?

Once drilled though a mains cable buried in a wall (after realising I was still alive) I fitted a socket as a means of rejoining the cables (and providing another mains socket).

Through crisps not that good on solid cores... solder heatsink in a box