[2] Leyburn was then imprisoned, and after being again released at the queen's request, he went back to Douai College, where he was employed in teaching philosophy and divinity.
Shortly before the English Civil War broke out, he returned to England, and in 1644 he was a prisoner in the Tower of London; there he met George Monck, and foretold that he would be a general in the north, and would eventually command the three kingdoms.
In 1647 he was sent to Ireland, with credentials from the court in exile, in order to bring about a better understanding between the two Catholic armies and James Butler, Duke of Ormonde.
[2] In 1648 Richard Smith, bishop of Chalcedon, then residing at Paris, appointed Leyburn his vicar-general in England, in conjunction with Mark Harrington, B.D., of the Sorbonne.
Later Leyburn was chosen president of the English College at Douai, on the death of William Hyde, and was installed by patent dated 24 June 1652.