For those who are fans of Celtic names, here are three posts I've written for Nameberry where I've analysed the most popular British Celtic names in their native countries:
Top Scottish Names in Scotland
There are no Ceridwens or Morags here; these are the names which represent the most popular in 2016 and 2017 in their homelands.
Seren and Dylan in Wales; Isla and Lewis in Scotland and Tristan and Jennifer (or Elowen) in Cornwall coming out top may not be surprising, but there are lots of gems lower down like Awel, Dyfan, Marsaili, Sorley, Sennen and Lerryn.