The site is not accessible by road so all heavy loads must come in by rail.
This includes loco coal which is transferred to tenders in the traditional way.
The links illustrate the process using photos from the Didcot Railway Center website and are copywrite
The posted photos later are own.
http://www.didcotrailwaycentre.org.uk/g ... hed_02.jpg
This shows the coaling stage with the shed water tank on the roof.
The stage is approached by an earthen ramp up which the wagons are propelled.
http://www.didcotrailwaycentre.org.uk/w ... 066_02.jpg
http://www.didcotrailwaycentre.org.uk/w ... 67_01m.jpg
These two links show traditional Great Western loco coal wagons and a modern wagon repainted to display the style of these earlier wagons.

Loading the tubs from the wagon

The loading platform over the tender

The tub run out onto the platform

Tipping the coal into the tender
The tubs were used in preference to a modern coaling tower as South Wales Steam Coal is liable to break and the tubs allowed grades to be separated for difference classes of service