The first attempt to free the coin by using as special pair of forceps didn't work, however, the second effort seems comical now, but no doubt wasn't then, involved a machine devised by Brunel (I'm not too sure that it was designed for this purpose) that eventually shook it loose.
Thank goodness this great man didn't choke to death, or we would not have had that wonderful bridge that spans the River Tamar between Devon and Cornwall or The Great Western Railway terminus at Paddington.edit.