Hello, Kharis,
After logging my query with you I later worked out that Widget functionality may have been changed by a WordPress update. Whereas [Table ID=N /] displayed the table correctly before when placed in an HTML widget, it no longer worked (as I had indicated). What you see now is the result of my fix by placing the shortcode [table ID=N /] in a Text widget instead. I daresay I should have done that in the first place a few years ago!
I log this now for future reference for anyone interested.
Once again thank you for your help. It is always very much appreciated.