I should have remembered this: one of my MacGregor forebears was named Walter Gregg. His branch was fairly prolific, and thus I number my cousins in the dozens; yea, even to the sixth degree (e.g. 1/64 consanguinity).

There is a wonderful photograph taken in my grandfather's yard, of 7 male Greggs of varied surnames. Every single one of them was a Walter! but perhaps half were called something else.