Employment expenses - ordinary commuting

A man is employed by a UK provider of rail maintenance. The employer sends our man to attend and make good repairs and resolve incidents at site; invariably all over the place. The employee uses his own car, and has to pay all tolls, parking etc etc. he receives no benefits from the employer. He makes no claim for mileage to his employer. He drives directly from his home to site, wherever that may be.

Is our guy allowed to claim his mileage as employment expenses against his Sch E income?

There is no permanent place of work as he gets directed to attend by the employer wherever repairs are required to be effected.

Thoughts?