At the age of 76, should he be considered old or not, his intentions were honourable!
Unfortunately he'll be a silly (old) boy if he proceeds through the courts. The photographic evidence does his case no favours. In addition, the highway code is quite clear;
Rule 219:
When [an emergency vehicle] approaches do not panic. Consider the route of such a vehicle and take appropriate action to let it pass, WHILE COMPLYING WITH "ALL" TRAFFIC SIGNS. If necessary, pull to the side of the road and stop, but try to avoid stopping before the brow of a hill, a bend or narrow section of road.