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Hi CML.
I really don't think that is a Perthshire paperweight. P21 is not a company code, and a PP21 is a swirl design. Yours might even be Chinese.
Regarding images, resize to under 100 KB according to your image processing software, and it should be okay. It is quite common to think your image is small enough according to the software (eg 118 KB), but to find the file size is a little to big in reality.
Alan