About the Welsh...I do not know enough Welsh history but I am not aware of a huge catastrophe...chronic hard times to be sure...but not a diaspora..but I could be wrong...big chunks of Wales did not move to a fairly hostile land sleeping 20 to a room and having a life expectancy measured in days...which is not to minimize the difficult lives they undoubtedly had..in coal mines in particular..in Pennsylvania, Michigan, where my Welsh greatgrandparents ended up..in Washington state...but my feeling is there were never huge numbers of them clustered anywhere..I am not even sure what language they spoke...and since I believe they were Protestants, if they came to a Protestent majority country, they probably did not face as much religious discrimination as Catholic perhaps...mg