Re: This requirement for paper bills/statements...
"the official address in the Royal Mail DB"
When we moved into what had been my parents' house we'd get stuff addressed with a name that only had 50% agreement with the name that had been carved in 6" high stone letters beside the gate for the last 30 years or so. It turned out that PAF had always had this incorrect variation. I wondered what the procedure was for getting it corrected. No problem, just call them up, no checks or anything. That was nearly 20 years ago so things are probably a bit different now although I suppose I could always refer them to the Streetview image.
At one time the house across the road had a nameplate on the gate and one on the house with different spellings.