Escape key doesn't close window

[NextDesign1]

When pressing the escape key, one would expect the window to close. Currently however, it causes the contents of the window to close, but the window remains open.

I have tried both defining the eventFilter, which picks up keypresses, but not escape, and overriding keyPressEvent, which has the same behaviour as eventFilter.

class Boilerplate(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        ...
        self.installEventFilter(self)

    def eventFilter(self, widget, event):
        if event.type() == QtCore.QEvent.KeyPress:
            print 'press'
            if event.key() == QtCore.Qt.Key_Escape:
                print 'escape'
        return super(Boilerplate, self).eventFilter(widget, event)

class Boilerplate(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        ...
        self.keyPressEvent = self.newKeyPressEvent

    def newKeyPressEvent(self, event):
        print 'press'
        if event.key() == QtCore.Qt.Key_Escape:
            print 'escape'
            self.close()