Thanks Jen.
In following your lead you helped me get to the steps I was looking for to prevent links in Outlook 365 from taking me to Edge instead of my default browser.
I think it was pure luck that I landed on this little 'gem' from last July.
How do I change my default browser in Outlook 365?
Open the Outlook Desktop App and go to File > Options > Advanced > scrolling down to Link Handling and changing the “Open hyperlinks from Outlook in:” option from Microsoft Edge to Default Browser and then clicking OK.
Phew - problem solved.
Note: It would have helped the readers of my post if I framed my issue better. DONE.