i don’t know much about this tune; could be English. around here it’s inevitably followed by Bonny Kate (not the Irish one; https://thesession.org/tunes/2452). Wood & Cutting recorded the same set on "Knock John".
There are a couple of tunes with this name from Sussex and Devon. The Fiddlers Companion has something interesting to say about them
It is of course the tune from Sussex (England) that you have posted, rtarnell.
Foor the benefit of anyone interested, Bonny Breast Knot (Devon, England)) is another fine English tune - and totally different from the Sussex one.
Both tunes are associated with dances of the same name, so the tune that is the subject of this particular posting might perhaps be more appropriately be classified as "barndance", rather than "reel".
I’m told that there a third tune (different again) also called "Bonny Breast Knot", though I’ve never been able to track it down ….
Bonny Breat Knot
Cutting & Wood do it in D. I have only ever played it in G and only ever heard it at sessions in G
"Devon" Bonny Breastknots
I know this posting is the "Sussex" Bonny Breastknots, but the Devon tune of the same name which has (inevitably) been referred to is to all intents and purposes the first two parts of the "Jolly Tinker" (q.v.), usually a five-part.