Paul Scott wrote:

If as others have said, numbers throughout the 020 area are 'virtual' can
these numbers be retained by someone moving elsewhere in the London area,
and as numbers are recycled, will 3,7 and 8 appear everywhere?

Let's put it this way. There are two big phone providers in the London
area, BT and Virgin Media. Numbers are portable between carriers and
within carriers subject to a few limitations and possible costs
depending on the circumstances. As time goes by, the geographical
correlation will reduce with porting but given the size of the existing
user base, it seems unlikely that it will disappear entirely. Recycled
numbers tend to stay in the same place.

To add to the confusing mix, a VoIP provider, like Skype, can give you
an 020 number (just one of many available UK STD codes) and so this
clearly does not lend itself to any meaningful geographical
interpretation. They're just numbers.

ESB