Actually I understand the Windows 10 App does allow collection of emails via POP rather than IMAP. There are several articles on the internet showing how to do this. However if it doesn't allow import of stored folders/messages from elsewhere then that doesn't help me. I had felt that if using Windows 10 (Microsoft) it would be better to use Microsoft's own Mail App but it just doesn't seem to be suited to my needs. I will therefore probably use Thunderbird as this DOES cater for up to six email accounts, using POP3, local storage in folders and the ability to transfer the entire setup including storage folders from machine to machine when one changes laptop.
"If you download mail into both WLM and Thunderbird before deleting it from the server you will have backup copies." doesn't help me at this point because I have already deleted all emails from all servers. I always do this immediately after collecting in WLM (which is why I need to copy the local mail storage folders to the new laptop). However, if I end up continuing to run both the Windows 7 laptop and the Windows 10 laptop for the time being, then once I've set up Thunderbird and imported the storage folders I will download to both WLM & Thunderbird before deleting. (This can however be a problem with a gmail account using POP3 as gmail doesn't like downloading in POP to two places)
I certainly don't wish to pay for a mail client host programme.
I am in UK
Thanks again for your help