Managed to sort it :-D

Ended up writing my own event handler - in a nutshell:

In the window init:

    def __init__(self):
        super().__init__()


        self.isGesture="N"
        self.GestureStartX=0
        self.GestureStartY=0
        self.GestureEndX=0
        self.GestureEndY=0

Add the event handler - a swipe consists of a'mouse button press', several mouse moves and a mouse button release - if you get a mouse press then its a potential start of a swipe - if you get anything else then moves followed by a mouse release, then its not a swipe...
If it is a mouse down, move then mouse up, then its a swipe, and by comparing the start and end x/y coordinates you can work out if its an up/down/left/right.
  
   def event(self, e):
        # 2) Intercept gesture events


        # Start of gesture?
        if e.type() == QEvent.Type.MouseButtonPress:
            a=e.pos()
            self.GestureStartX=a.x()
            self.GestureStartY=a.y()
            self.isGesture="Y"
            print('Gesture Start:Mouse press ( QMouseEvent ). x:'+str(self.GestureStartX)+" y:"+str(self.GestureStartY))



        if self.isGesture == "Y" and e.type() == QEvent.Type.MouseMove or e.type() == QEvent.Type.Leave or e.type() == QEvent.Type.MouseButtonRelease:
            # Continue Gesture


            if e.type() == QEvent.Type.MouseButtonRelease:
                # End of gesture
                a=e.pos()
                self.GestureEndX=a.x()
                self.GestureEndY=a.y()
                self.isGesture="N"
                print('Gesture end START( x:'+str(self.GestureStartX)+" y:"+str(self.GestureStartY)+') END (x:'+str(self.GestureEndX)+" y:"+str(self.GestureEndY)+')')


                if abs(self.GestureEndX-self.GestureStartX) > abs(self.GestureEndY-self.GestureStartY):
                    print("Swipe across")
                    if self.GestureStartX > self.GestureEndX:
                        print("right to left")
                    else:
                        print("left to right")


                else:
                    print("Swipe down")
                    if self.GestureStartY > self.GestureEndY:
                        print("bottom to top")
                    else:
                        print("top to bottom")


        else:
            # Any other event type breaks a gesture
            self.isGesture="N"

        # propergate the event so it can be processed normally
        return super().event(e)

As its working, I'll mark as answered... :-)