Help dating these plates.

[tcolgate]

Would anyone have any ideas on a date for these, or maybe a way of dating them? There's no expiry on the packaging. I think the label style is later. I'm assuming '60s or '70s. I'm not sure when they stopped making p300, or coating glass. The data sheet includes recipes for D61a, D-190, D-167, and F-53 and F54a fixers. They may have been packaged (or manufactured?) In London.
I have 3 boxes. The emulsion is surprisingly fine for a fast film. They are very fogged, but I'm still getting some fun results.
I can't find any old product catalogues with plates listed (I'm sure I did find one a few months back). Looking a various museum items with the similar styling, early 1960s seems likliest.

 

[tcolgate]

They could be earlier if the National Trust dating is accurate
Box of Kodak P.300 Rapid Panchromatic photographic plates. 1525333 | National Trust Collections https://share.google/XaeCcpxv7BacbIFQq

 

[Molli]

Maurice Fischer's 'Photo Memorabilia' is my go to source for dating papers and films. The closest match to your plates seems to be in the Kodak Sheet Film Section around 1965:

Kodak Black & White Papers

Kodak

photomemorabilia.co.uk

I have some 8x10 Kodak Photomechanical Film in my stash with the red boxed Kodak logo alongside the black boxed descriptor matching the style of your plates and it shows the faintest stamp reading 10 APR 1969.

The labels changed again in 1970. Mr. Fischer has very kindly and assidiously shown packaging from both England and the United States so, hopefully, you'll be able to form a more confident estimation of your plates' age.