I need some shortcrust pastry advice, please

[Melbourne12]

I'm the first to admit that I'm not the world's greatest pastry maker.  But I normally manage to be at least competent.

The other day was a major FAIL, though.  My technique for shortcrust is to put the flour and (cold) fat into a food processor, blitz it fairly briefly until it gets to the crumb-like stage, then decant it into a bowl and mix with ice-cold water until the right consistency is obtained.  On this occasion I used 1 part by weight unsalted butter to 2 parts by weight plain flour (plus a little salt), a tried and tested formula.

The problem was that the butter didn't combine properly with the flour.  The fat was cut into tiny specks, but it didn't "stick" to the flour to give that crumb-like effect.  Perhaps foolishly, I continued to the next stage, but the resulting pastry was almost inedible - it remained a flour and water paste with tiny specks of butter in it.

The only difference that I can think of is that I used a different brand of flour to my normal ones.  It was Waitrose own brand plain flour, but I find it difficult to believe that this could make much difference.

So, can anyone with pastry magic in their fingers tell me where I went wrong?  Thanks in advance for any guidance!

[Melbourne12]

[pg]

Wondering if the butter was too cold? The foodprocessor blitz is trying to emulate the rubbing-in phase after all which when done by hand will tend to melt the fat slightly through the warmth of the fingers moving through the mixture.

If it happens again perhaps start the pastry off in a low oven to give the fat a chance to melt and mingle through the mixture a bit?

[peanuts]

I always make my shortcrust pastry (same quantities as you, with a little sugar if doing a sweet pastry) in the food processor entirely.  I let it rub in longer than you, then trickle in cold water, very slowly, until it seems the right amount (better to add less as you can always add more if not enough),   letting it go on mixing, and gradually it starts to come together, then get  into a clump that  starts to go round and round, picking up loose bits, at which point I turn it off - perfectly mixed every time. 
I also add lemon or orange zest, if sweet, or herbs if savoury.  And from time to time a good handful of grape nuts, which makes it  beautifully crunchy. Our French friends here always ask what I've put in it!