Complex sentence: The survey was produced at a scale of 1 inch to 1000 yards (1:36,000) and included "The Duke of Cumberland's Map" (primarily by Watson and Roy) now held in the British Library.
Split into simpler sentences: The survey was produced at a scale of 1 inch to 1000 yards (1:36,000). The labours of Watson and Roy, in particular, resulted in "The Duke of Cumberland's Map", now in the British Library.