Please read the release notes. https://www.mozilla.org/en-US/thunderbird/52.1.1/releasenotes/

The only item which could apply to me is the printing of blank pages in certain circumstances as being unresolved. The circumstances are not specified so I am not sure whether I should be changing the configuration or, if for that matter, I know how. I am not very technically-minded.

You stated you get blank pages only. Sounds like a good match to me. Follow this link. Go to comment 35 and follow the instructions for a temp fix. https://bugzilla.mozilla.org/show_bug.cgi?id=1353625

I warned that I was not very technically-minded! How does one "open about: config" and "close about: config"?

Here's a simpler method that may work: change the paper size in the printer's Properties from Letter to A4.

Thank you for the suggestion but my printer is already set to A4 (it does not have a "letter" setting).

The printing bug should be fixed in the near future, and in the meantime I suggest this workaround: select File/Save As/File..., select HTML for 'Save as type', and open the file in your browser, Print.

Many thanks for your assistance - it worked. I had previously tried copying as a document and then printing but it did not work. Changing to HTML did the trick. By coincidence the H stands for Howes!