The various codes for these things varied a little in the U.K., depending upon the location and which precise part of the "old days" we're referring to!
In the old-old days (pre-STD) the codes 951, 952, 953 etc. were used for inquiries, directory, the speaking clock, etc. (Again, from some minor exchanges one would have to use a routing digit first, so they would sometimes become 9-951, 9-952, etc.)
999 was the emergency number of course, although the switching/trunking in some places meant that you'd reach it after dialing just 99.
The general operator back then was simply 0. That was in
most of the country.
In the director areas (those cities with 7-digit local numbers, i.e. London, Birmingham, Edinburgh, Glasgow, Liverpool, and Manchester) the equipment used a whole series of 3-digit service codes, e.g.
TIM (846) TIMe
DIR (347) DIRectory
ENG (364) ENGineers
INF (463) INFormation (general inquiries)
TEL (845) TELegrams
UMP (867) UMPire (Cricket scores -- This
is Britain, old chap!
)
There were also two separate codes for long-distance operators from director cities:
TOL (805) TOLl operator
TRU (878) TRUnk operator
TOLl was for calls outside the London (or Birmingham etc.) area but still relatively short-haul, while TRUnk was for everything further afield. In most other parts of the country you just dialed 0 and asked for the number, although sometimes there were special codes for operators handling nearby but non-local calls.
In the slighty newer old days (late 1950s/early 1960s onward), STD came along and used the zero prefix, so the general operator moved to 100.
Many other services were moved to or later added to the 1 level as STD spread and letters were dropped, rendering the director codes obsolete, e.g.
151 Engineers / Faults
16 (or 160) Dial-A-Disc / Cricket
191 General inquiries
192 Directory
190 Telegrams
The speaking clock, as mentioned already, became 123 in London and usually 8081 in the provinces (until that too changed to 123 sometime during the 1980s).
There were other local variations and changes over time though. At one point in London, for example, the GPO split the directory service so that you dialed 142 for numbers within London and the usual 192 for numbers anywhere else in the country. I seem to recall that the international operator was 107 at one point as well, although in later years (and still today) we ended up with:
153 International directory enquiries
155 International assistance
The 17x codes were (and still are) used for a variety of engineers' numbers -- ringback, automatic line test, test tones -- all unpublished, of course.
The privatization of BT in the early 1980s and the formation of Mercury Communications in competition set off the start of alternate carrier prefixes: Initially 131, 132, and 133 for Mercury, then 144 for BT's own chargecard service, and gradually expanded until today we have literally
dozens of 1xxx codes to route via different carriers.
Of course, 192 has gone now and other codes have been added piecemeal to cater for new services: 141/1470 to withhold/release CLI, 1471 for last-number readback, 1571 for BT's C.O.-based answering service, and so on.
