Michael,
Perhaps you can be excused, as the UK and Ireland mostly didn't use airbrakes in the steam era, but have a look at these photos from your web site. The 2-6-0's were equipped with two Westinghouse 11" airpumps, as shown in your photo of #11. The cab photo is of a Westinghouse airbrake control valve. The larger 40 and 50 series 2-8-0's were equipped with a Westinghouse cross compound air pump, as shown in your photo of #53.
I know that the G&Q has normally used brakemen riding the tops of the freight cars to operate the hand brakes. With 5.2% grades on the line, this would seem to be a wise precaution, even if the brakes were reliable. Given the condition of much of the mechanical equipment in later years, I'm guessing hand braking is now a necessity! At least one of your photos shows the brake hoses that are hanging down between the tender and first car are not connected up.
Michael Allen