Looked up Welch on internet surname site...

Wallace, Wales or Welch, and formed thus--Gaulish, Wallish, Wallis, and also Welsh or Welch, a name given to the Britons by their Danish and Angles invaders, because they originally came from Gaul.

The welsh surname for the English is Sayce, - sais "English speaking". Which is similar to the scottish Sassenach.

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