Thank you,
I tried out my basic idea with friends of mine and between my two email addresses.
I created my 3 column, 19 row table in Thunderbird: Tools, New message, insert Table, Save as Template.
Then in Thunderbird Templates, Enter as new message and emailed the table with instructions to my testers.
They could see my table and entered Reply or whatever in a variety of email clients. In the Reply window they were able to click in an appropriate cell and key in stuff.
They then could click Send or whatever and the completed table would come back to me.
I don't know whether all this was in by HTML or what but it would be great if it all could be automated / tidied up.
TableTo 0508.eml