An employee is a customer support manager for a computer company. He normally drives the 9 miles to his permanent workplace. One day he has to visit a client to sort out some problems with a computer. The client's premises are only a mile from his permanent workplace. His journey to the client is the same length as his ordinary commuting journey and is in almost exactly the same direction, although he does not follow exactly the same route.
The client's premises are a temporary workplace. The employee's
journey to the client is in almost exactly the same direction as
his ordinary commuting journey and it is the same length. So it is
substantially ordinary commuting, see
EIM32300. No deduction is due for the
cost of his travel.