I was interested to read this post. My great great grand mother was born Jane Turtle (1820-1903) and she married my great great grand father Rev John Montgomery of Glen Whirry (1797-1869). Her father was a Lancelot Turtle from Aghagallon and ? died 1828. There were subsequently 3 Lancelot Turtle Montgomery's therafter. The first was also a Tea Merchant (Pratt & Montgomery - Nambarrie Tea) like Samuel. Jane's father was reputed to be a Quaker but the Quakers have no record of him so he was probably an adherent and not a full paid up member. I have tried in vain to research this branch of the family. More recently there was a famous Irish Ornithologist called Lancelot Turtle (and a quaker). I have just had a letter from a old University friend who was born Turtle and lives in NI and she plans to collate her family records soon- so hopefully that might yield something.