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HMRC internal manual

Employment Income Manual

Travel expenses: travel for necessary attendance: duties defined by reference to a particular area: example

An employee is a relief manager for a chain of regional tourist board offices. He shares responsibility for providing cover for all of the offices. There is no regular pattern to his work.

None of the individual offices is his permanent workplace, see EIM32065. His duties are defined by reference to a particular geographical area and so that area is a permanent workplace, see EIM32190.