Complex sentence: The Dutch had remained suspicious of the negotiations and fearful that their interests were being neglected; it was an apprehension was justified, and after much cross-Channel diplomacy the final proposals were agreed between France and Britain.
Split into simpler sentences: The Dutch had remained suspicious of the negotiations and fearful that their interests were being neglected--an apprehension that was justified. After much cross-Channel diplomacy the final proposals were agreed between France and Britain.