Pete, are you hand mixing this dough or using a food processor? I prefer the processor but it's easy to overmix. A few quick pulses are usually enough. If it looks barely mixed it's perfect. Dump it out and the rest will take of itself during the rolling out.
Also I'm sure you know but start with everything (bowl, spoon, water, butter etc) ice cold. Use ice water not cold tap water.
Also I'm sure you know but start with everything (bowl, spoon, water, butter etc) ice cold. Use ice water not cold tap water.