Are the blackthorns that late in Derry? They come way before the mayblossom(hawthorn) in England, and that is now well open in the south, just opening in the midlands, and soon to come in the north. The blackthorn was out ages ago everywhere. Could you give a rough date for blackthorn and hawthorn in Derry? This is very interesting. the mayblossom has advanced by a couple of weeks(ish) in most parts of England in the last twenty years, incidentally..global warming!!
   The line in an English may song
"It's naught but a sprout
But it's well budded out"
shows clearly that at that time (and place) the May blossom wasnt open on May Day. It would seem Mayblossom was always out in the 1700's, then started opening after Mayday till very recently, and has now gone earlier again.