Today, 06 Sept, is the 400th anniversary of the ship Mayflower's departure -finally- after a few months of struggle trying to get away. (Plymouth, Devon 1620)
The majority of people on the ship were Brownists, a faction of separatist Protestants eventually known as Puritans in England and the Pilgrims in North America, for whom the Church of England was still not anti-Catholic enough; they took Calvinism to the HNL (hole 'nutha level) and royally pissed off their neighbors with their holier-than-thou convictions about the corrupt worldly entanglements of the Church.
For the previous couple of decades, after Archbishop Bancroft had decided to actually enforce English laws against sedition and separation, these Puritan congregations had been acting on the down-low, and some had moved across to Holland to put some actual physical separation to go with their communal and bureaucratic rejection of English custom.
Luckily for them, though, they had some profitable entanglements of their own with anti-monarchical business interests that were willing to underwrite their decision to turn their neighbors' desire to see them gone into a virtue by setting up a new commercial colony.
https://en.wikipedia.org/wiki/Brownist
What markers have you visited in your tours of southeast coastal England around Plymouth, or in Leiden for that matter, that commemorate the departure of these folks?