An employee is a human resources manager who normally drives 9
miles to the office that is her permanent workplace. One day she
has to visit a factory to discuss possible redundancies. The
factory is 11 miles beyond her office. She drives the 20 miles to
the factory along her ordinary commuting route and past her
The factory is a temporary workplace. The journey from home to the factory is along the same route as her ordinary commuting journey but is substantially longer. So it is not substantially ordinary commuting. She is entitled to mileage allowance relief, see EIM31626.
This example illustrates the practice of not treating a journey from home to a temporary workplace as ordinary commuting where the extra distance is 10 miles or more each way, see EIM32300.