Anyone have any idea of how much rain fell.

http://www.huffingtonpost.co.uk/2013/07/30/flooding-west-yorkshire-pennines_n_3675182.html

I saw the report on this evening's Look North.  The flash flooding caused much damage to roads and properties in Walsden.  It was reported that 17mm of rain fell in 15 minutes, though the final total must've been much higher as it lasted 45 mins in total.