Complex sentence: 'It was suggested that James' body would be her exchange with Henry for the Duke of Longueville, who after his capture at Thérouanne by John Clarke of North Weston was sent to Catherine and lodged in the Tower of London.
Split into simpler sentences: 'It was suggested that James' body would be her exchange with Henry for his French prisoner, the Duke of Longueville. Longueville had been captured at Thérouanne by John Clarke of North Weston, sent to Catherine, and lodged in the Tower of London.