I'm a time-served electrician but served my apprenticeship and all my
working life in one factory or another, so I readily admit I have no
experience of the domestic side of the business, ie, wiring houses.

The factory where I served my time was brilliant and the apprenticeship very
varied. We had our own power house onsite with four "normal" turbine/genny
sets and two "specialised" sets providing a certain part of the factory with
whatever it required - can't remember now because it's been 33 years and
many thousands of beers since then )

One day I might be installing a new socket for a copier in an office, the
next day I might be jointing a 6,600V feeder cable to one of the 20
substations we had onsite and, having had such a varied and brilliant
apprenticeship, I'll be buggered if the guvmint are going to tell me I can't
install a new consumer unit under my own stairs!!!

So, what's the best/approved method of extending the cables from my old
consumer unit into my new one?

Thanks, Bill.