David Bradley wrote:

However there
is a rule that says if the frequency of any route is less than 10 minutes then
it is a candidate for fiscally advantageous to operate it as a trolleybus
route.

A rule, eh? As 'asdf' has mentioned, 'on your web site, you state that
"the opinion of the country's largest group of professional transport
planners is that the best option for most places is trolleybuses" '.
Did "the country's largest group of professional transport planners"
devise this rule? And, in any case, will you please tell us more about
this group?