The message
from Mike Barnes contains these words:

FYI I used Fugawi 1:50000, took the grid reference of Queensbury as
SE09962 30999, Bradford City centre as SE16462 32939 and computed the
difference by trig.

Isn't the length of the road(s) the important thing here?

Why on earth should it be? The distance was given to illustrate the
closeness of Queensbury to the city centre.

[...]

As to height difference the figures above give 809 feet but moving off
the main road in Queensbury it is easy enough to find higher ground.
1200 feet at the upper edge of Queensbury housing and 1227 feet a few
hundred yards further on at the top of the hill in the hamlet of
Mountain. In Bradford City centre within a few hundred yards of City
Hall the ground drops to 312 feet so I could have with almost equal
justification claimed a height difference of 900 feet at under 4.5 miles
distance.

Isn't the height difference between the ends of the road(s) the
important thing here?

That would be near enough 900 feet from a house in Mountain to one in
the city centre or 800 feet if you stick to the A road. But the water
main network would feed both the house in Mountain and the lowest one in
the city centre.

428 feet AMSL (711 feet down from Queensbury) would put you part way up
Little Horton Lane, outside the city centre.

--
Roger Chapman