Indeed, a Danish army invaded northern England just three years after William I’s coronation. The French then took up the task, and their 1216 invasion saw Louis VIII of France briefly proclaimed king. Henry II, Henry IV, Edward IV, Henry VII and William III (pictured) all took the throne at the head of invading armies, most of which contained troops that served foreign crowns.
England and Scotland invaded each other repeatedly before unifying in 1707, while the most recent invasion took place in 1797, when 1,400 drunken French soldiers landed in Wales and caroused for three days. It doesn’t rank among the upper echelons of attempted conquests, but it still counts.