According to www.familyassistant.com the 1881 UK census only lists 2872 people with the surname Heron. This to date , according to the same site (your guess) stands at 4931. We know 6 in Scotland plus Michael (Mick) Heron, a possible cousin in the US.
The same site states there are only 3038 Herons in the US at date.
John + Margaret