Hmm...What strikes me is the Mary Hopkins signature. People began to notice her in the late 60's. Her professional relationship with Paul McCartney started in 1968. I have a feeling her signature could have been added years later.
I think that timeframe is right, but like was stated, Mary Hopkins was not associated with the Beatles at that time at all. So her being on there is suspicious to me.
Would these really look right even without the Hopkin angle?
The Starr looks a lot looser than usual, the "G" in George looks atypical (maybe more like earlier examples) and the "artney" seems very flat to me. Lennon's inscription/sig is also very loose but looks better to me, though the last part of Lennnon looks a bit tighter and neater than normal - especially the "nn".
In being fairly specific I realise that I have opened myself up to being shot to pieces here. Fire away with examples that prove me wrong.