Bruce Schneier, an internet-security expert, thinks it is a bit like worrying about spammers stealing a copy of the telephone directory.

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The cash was to buy a confidential directory of the royal family's landline telephone numbers, and all the phone numbers - including mobiles - of the household staff.

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Sometimes the NKVD simply picked Polish-sounding names from the telephone directory, or arrested en masse all those attending a Polish church service.

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On another occasion, a man contacted BT, giving Miss Dando's ex-directory telephone number and address and asking for her line to be changed to his name.

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