The solution was relatively easy.
From within eM Client, File > Import > i__mport from folder with .eml files
For Windows Mail, the store folder is :- C:\Users(yourname)\AppData\Local\Microsoft\Windows Mail (AppData is a hidden file, so just type it into the Windows explorer address bar and hit enter) you will then see the rest of the files to click on.
Once you have found your folder you need to copy the folder address into the eM Client window so that it can find it.
There is a box " include sub folders" that you need to tick.
Also need to tell eM Client where to store the new mail folder - anywhere you like will work.
Click finish, sit back and wait while the software does it’s magic.
I had 16 years worth of email which included some lost stuff when Outlook Express crashed many years ago. Took more than 12 hours to bring in about 14,000 emails.
The file structure was kind of still intact, I think that earlier crashes in Outlook Express had made the whole thing confused.
An hour or so of re-organising and I have much more than I expected - a complete email record.
Look and feel is pretty similar to Windows Mail, with a couple of extras.
Found you cannot search with part of an email address like I could previously, but heyho, its a reasonable option.
Just need to see if it’s worth the cost now ( I have two PC’s at home and 4 email addresses), so there is a requirement to purchase two pro licenses which appears to be more than £100 for the lifetime upgrade option.