After Lord Grantham has told the family about the letter he has received from Mr Murrey, he says "and now we should go into dinner before Mrs. Patmore blows a gasket". However the expression "to blow a gasket" did not come into use until the 1940's. The episode is six months after Matthew's death and his gravestone establishes that he died in 1921.
The English and Scottish slang term "crack" found its way to Ireland under the variation "craic," but the new spelling did not find its way to England under the new spelling until the mid-Twentieth Century.