But the scholarship, if always serious, was generously shared with anyone, however humble, who came within his ambit. He knew that heraldry and genealogy interested a wide range of people, and to any who needed his help he gave it, freely and patiently, but not without a sense that the subject was too important to be frivolously bestowed.
Heralds and Heraldry in the Middle Ages is a short book, but wide-ranging in its learning. More important, it put the history of heraldry where he knew it belonged, in the centre of historic research. The records of the activities of heralds, a potent political force well into the 18th century, were thus of paramount importance to him, and this sense informs everything he wrote, especially the great Heralds of England. His own contribution to the Roxburghe Club, of which he was a regular attender, was the publication of Stephen Martin Leake's Heraldo Memoriale: or Memoirs of the College of Arms 1727 to 1744, in 1981. This work, besides recording (not without malice) the later career of his hero John Anstis (like himself and Leake Garter Kings of Arms) demonstrated the vitality of the College in a rather neglected period.
His own contribution to the maintenance of the college, as pursuivant, herald and finally king of arms, was of unequalled importance. He strengthened its officers, raised funds for its fabric and created the museum. His persistence and ingenuity in pursuing these goals were limitless. One famous example was the full completion of the card index of names mentioned in all the visitation records. This, begun by volunteer workers but left unfinished during and after the war, was languishing in a basement. To Wagner came a deputation of Mormons in search of records of names for retrospective baptism. He seized the opportunity: funded by them, the index was completed and the whole transferred to microfilm as part of the International Genealogical Index.
He had a great enthusiasm for Rolls of Arms, and the two Harleian Society volumes (to which, characteristically, he gave the name "Aspilogia", coined by Anstis) cataloguing them will be a permanent memorial. But his greatest work in this field, which he lived, not alas to see, but to have read aloud to him, was Medieval Pageant, the magnificent reproduction of "Writhe's Garter Book", most beautiful of all English medieval heraldic manuscripts, presented to the Roxburghe Club by the Duke of Buccleuch and even now in the process of distribution. The long text that accompanies this was partly written and wholly inspired by him. It is a monument to all he set out to do in his life and work.
If you shared Wagner's interests, and it was not difficult to catch his enthusiasm, he was a lively and amusing companion, not in the least intimidating, despite his serious manner. His weekly lunches with his much loved colleague Hugh Stanford London were a delight, and he and his wife Gillian were generous hosts, particularly in his last years of blindness when he could no longer get about. He bore this without complaint, and in this, as in his work, left an example that those who loved and admired him can only hope to follow.