I often don't tell musicans that i have pp, as they assume that i'm arrogant and start to treat me differently.
These days instrument tuning is set with A above middle C at a frequency of 440Hz, in the baroque period it was "somewhere near" 415 Hz (they didn't have so much in the way of sophisticated equipment to get the exact frequency every time) 415.3 Hz is G#/Ab in modern tuning so Mat is correct if going by present day tuning standards. He was given no clue that the piece was played in Baroque period tuning, as I said in my post above Colin was sneaky!