UK Telex Directories - Answerback Codes

[M1ECY]

Something that seems strange after studying the UK Telex Directories I have here is that of Answerback Codes.

The 1974 Directory has two sections, one searchable by subscriber name,the other by answerback code.

We are all used to the format 123456 Business G, but the directory appears to suggest that the answerback code is just "Business name" with no numbers - Reailse that most members here are not UK experts, is this situation the same in directories from other countries, or has the UK done it's own thing and decided not to put the machine number on the answerback?

Perhaps the answer is just as simple as the number is not added to the search by answerback section?

Cheers
Sean