British typesetting style is a little different from US style in the way dashes are presented. In the UK, you might see a thin-space--en-dash---thin-space where

British typesetting style is a little different from US style in the way dashes are presented. In the UK, you might see a thin-space--en-dash---thin-space where a US typesetter would use a em-dash. Typewriter style generally follows books style. Since typesetters no longer use an extra space after punctuation, it's vestigial in typing.