The map covers mainland Britain and out to the Western Isles of Scotland, but unfortunately doesn't include Northern Ireland, nor does it show the Orkney and Shetland Isles to the far north.

Also not shown are the Isle of Man and the Channel Islands, which although politically not part of the United Kingdom were/are an integral part of the U.K. telephone system.

As a general rule, under the STD system calls made to an adjacent charge group were still classed as local, but in a few places this was not so, and these boundaries are marked by heavier lines between charge groups on the map. These exceptions were typically in thinly populated areas where open moorland or a small mountain range provided a natural boundary between communities of interest.

Under the original STD system - which survived right through to the 1980's - calls within one's own charge group and to neighboring charge groups were local (except as noted above), calls beyond that up to approximately 35 miles were STD "a" rate, and calls over 35 miles to anywhere else in the country were STD "b" rate.

A special rate applied to call to the Channel Islands, even though part of the U.K. system.

P.O. ENGINEERING DEPARTMENT EDUCATIONAL PAMPHLET - DRAFT SERIES

TELEPHONES 4/1

UNISELECTOR MECHANISMS

P.O. ENGINEERING DEPARTMENT EDUCATIONAL PAMPHLET - DRAFT SERIES

TELEPHONES 1/1

1 Issue 2 3/60

LOCAL BATTERY AND CENTRAL BATTERY TELEPHONES

Keysender , keycaller No. 5

British Post Office Standard Dial No. 8

from the book: Automatic Telephone Systems by William Aitkin Vol. 2 London 1923, page 209 - 213

Source:

TELEPHONY
A DETAILED EXPOSITION OF THE TELEPHONE SYSTEM OF THE BRITISH POST OFFICE
BY T. E. HERBERT, M.I.E.E. FORMER SUPERINTENDING ENGINEER, G.P.O.
AND
W. S. PROCTER, A.M.I.E.E. REGIONAL ENGINEER POST OFFICE ENGINEERING DEPT.

First Edition?? 1938
Reprinted? ? ?1938
"?????????????????1939
" ????????????????1940
"?????????????????1941
"?????????????????1943

Source:

TELEPHONY
A DETAILED EXPOSITION OF THE TELEPHONE SYSTEM OF THE BRITISH POST OFFICE
BY T. E. HERBERT, M.I.E.E. FORMER SUPERINTENDING ENGINEER, G.P.O.
AND
W. S. PROCTER, A.M.I.E.E. REGIONAL ENGINEER POST OFFICE ENGINEERING DEPT.

First Edition?? 1938
Reprinted? ? ?1938
"?????????????????1939
" ????????????????1940
"?????????????????1941
"?????????????????1943

Source:

TELEPHONY
A DETAILED EXPOSITION OF THE TELEPHONE SYSTEM OF THE BRITISH POST OFFICE
BY T. E. HERBERT, M.I.E.E. FORMER SUPERINTENDING ENGINEER, G.P.O.
AND
W. S. PROCTER, A.M.I.E.E. REGIONAL ENGINEER POST OFFICE ENGINEERING DEPT.

First Edition?? 1938
Reprinted? ? ?1938
"?????????????????1939
" ????????????????1940
"?????????????????1941
"?????????????????1943