I seem to recall stumbling upon that site some time ago as bits of it seemed familiar.
Bell made it a little easier to assign names by opting for the 2L-5N scheme instead of 3L-4N. The British scheme was also prevented from using names starting with the letter O by having it on zero instead of 6.
The old-style U.K. numbering was a real mixture of 3, 4, 5, 6, and 7-digit numbers.
Many small rural exchanges had 3-digit numbers, and with often less than 300 subscribers, chances are that only the 2xx, 3xx, and possibly 4xx ranges were assigned.
4, 5, and 6 digit numbering was usually in progressively larger towns. Many places had mixed length numbers. Certainly from the 1950s through to the 1980s, many medium-sized towns had their original 4-digit numbers in the 2xxx, 3xxx, and 4xxx ranges, with 5-digit numbering as 5xxxx, 6xxxx, and/or 7xxxx.
A trend in later years was for small rural exchanges to be placed into an integrated numbering scheme with its parent exchange. For example, where I once lived the original exchange was named Three Waters and had 3-digit local numbers. It was integrated with the numbering of Truro, the nearest town, and given 6-digit numbers of the form 560xxx. The official exchange name was then changed to Truro, even though the village was still served out of the same central office.
Many other smaller exchanges which "homed" on Truro were integrated in a similar way, and eventually the older 4 and 5-digit numbers in Truro itself were made up to the present-day 6 digits by adding one or two digits in front of the existing number.
7-digit numbering with directors was used only in the major cities: London, Birmingham, Edinburgh, Glasgow, Liverpool, and Manchester.
[This message has been edited by pauluk (edited 04-11-2003).]