If my maths is right in those 3.9secs at 37mph he covered 211.64ft. That's just short of the highway code stopping distance from 70mph. I don't see how he can fight it. Even on ice from 40 I'd expect him to have lost more than 3mph in 211ft if he made any attempt to stop for the light.
Even trying to argue the "amber means stop unless to do so would cause an accident" case would be abit lame as from 40mph 3 seconds isn't exactly an emergency stop.