He should have equalized midway through the half with only the goalkeeper to beat but his shot grazed the crossbar and he also guided a header wide before, after 36 minutes, he deflected Shane Duffy's powerful header past Butland from close range.
Having created a good chance for Gestede after stripping Philipp Wollscheid for speed, only for his team-mate to fluff his shot, King was fouled by Cameron in the eight minutes of stoppage time for three lengthy injury breaks.
The Stoke defender was shown a straight red card by referee Anthony Taylor and Gestede did not make a mistake with his second chance from the spot.
Rovers ensured there would be no turnaround of momentum in the second half as King – had scored five goals in his previous 68 appearances – twice raced through to slot the ball past Butland in carbon-copy goals within five minutes of each other.
Stoke were deflated and dejected and home fans took great delight in taunting their former manager.
It all got a bit too much for some of the visiting supporters, some of whom became involved in a minor scuffle with stewards and police late in the game.
Hughes ordered his players to go acknowledge what was left of the traveling fans at the final whistle.
It looked more like an offer of an apology but that should not take anything away from another impressive cup performance from Blackburn.
Mobile app users, watch the video highlights.