Ernest Kehr/1947 Centenary International Philatelic Exhibition Ephemera

Hi everyone. I thought I'd share some recently acquired ephemera pertaining to the 1947 Centenary International Philatelic Exhibition. Honestly, I haven't collected stamps since I was a kid (though have thought about getting back into it at some point) and bought this mainly because it was interesting, and cheap. I also remembered having a souvenir sheet featuring the the first US stamps as part of my childhood collection.

The first item is a letter on Exhibition letterhead from and signed by Ernest Kehr thanking someone named Pat for their help with the exhibition (any idea who Pat might be?). The second is a large postcard for the exhibition with an exhibition postmark. I do know that Ernest Kehr was a well-respected philatelist and author, based on an internet search. Any additional info about these pieces would be much appreciated. Enjoy!