In September 1442 he was appointed to the Embassy to negotiate peace with the French king, led by Richard Duke of York and Cardinal Louis (who was then in capacity as Chancellor of France). He was in a renewed commission under the Earl of Suffolk, appointed in February 1444, which concluded a truce at Tours which lasted until 1450. In the course of these negotiations the marriage between Henry VI and Margaret of Anjou was arranged by the Earl of Suffolk, and in July 1444 Thomas Hoo was appointed, and in August sent with Sir Robert Roos and the Garter King at Arms, to be in attendance upon Margaret until her landing in England in April 1445, when the marriage was solemnized. During the intervening period she was espoused to the king by proxy in the person of the Duke of Suffolk.