Ah, same here too - 1907 house and plaster which hasnt been renewed since. Did the same myself one, cost me £1200 in labour to get patched up again - learnt my lesson there then....
Don't tell me this - I'm getting busy with a hammer later today. I think I might use the gentle tap-tap-taperoo method instead of putting the Ace of Spades on and screaming 'Banzai!!'