Grant Allen - Biographies of Working Men стр 9.

Before the Hetton railway was opened, however, George Stephenson had shown one more proof of his excellence as a father by sending his boy Robert, now nineteen, to Edinburgh University. It was a serious expense for a man who was even now, after all, hardly more than a working man of the superior grade; but George Stephenson was well repaid for the sacrifice he thus made on behalf of his only son. He lived to see him the greatest practical engineer of his own time, and to feel that his success was in large measure due to the wider and more accurate scientific training the lad had received from his Edinburgh teachers.

In 1819 George married again, his second wife being the daughter of a farmer at Black Callerton.