Many thanks for your feedback Peter. Most grateful. I did initially try to sort this matter out with my hosting company, Site5. They suggested ensuing that all my plugins and themes were up to date which I did. My WP version is the latest version too. Still got the white screen though when I upgrade to version 5.5 which, incidentally, is the latest version that Site5 offers. Perhaps I should try a different theme? Is Site5 sufficiently reputable?
Kind regards, Richard