I know you probably already know this but clues to telling its a PP =

1) Photos returned unsigned
2) No personalisation

It could be presigned until you hold it upto the light and check if the signature is on the photo or part of it.

Or if someone gets the same PP as you.

Thats how I would go about it 8)

unfortunately its pre printed he's just updated the pp cards he sends out to a different newer photo

on 27th January 2011, I wrote to David Beckham c/o one of the English Football Clubs. He had come over to the UK to play a few games around February 2011. I cant remember which Football Club - sorry - but the address wont be valid anymore anyway. I sent a LOR, SASE and two photos. Today I received my SASE back, and photos unsigned, but included was a small 6x4 photo with a signature on it - not sure if it is genuine or printed??? i had totally forgotten about this one, so pleased to see an old request come back!!!
http://imageshack.us/photo/my-images/560/dscf9702.jpg/