The Ordnance Survey map was provided by OS Openspace.
Maps can take a little time to be read-in. This depends on your choice of browser and also the size of your processor and your internet speed. In addition to the fully expandable OS map this map has an overlay of Roy's roads held in a large database of coordinates. You may need to be patient when loading-in and also when panning.
The roads are highlighted in semi-transparent blue and the effect is that of a rather thick highlighting pen. This becomes less obtrusive as the map is enlarged.
In addition to the panning and enlargement tools on the top of the screen the map may be re-centred by ‘dragging’ with a right-clicked mouse. It may be enlarged by double-clicking.