This work is by far the most comprehensive and informative Biography of Henry V I have yet to come across. Unlike quite a few others it covers Henry's life in its entirety, and devoted whole chapters to Henry's early years and upbringing.
Most importantly perhaps it provides a sound, objective, and reasoned analysis of Henry as King and man. Whilst other more and less recent Bios take extreme positions and cite Henry's negative or controversial actions and decisons to demonise him, bash him or prove that he was evil and heartless, (most notably Ian Mortimers) or else take the opposite extreme of Lionising Henry to a near Godlike status akin to theat of his characters in Shakespeare's play.
Allmand does neither of these, instead he takes the Middle ground and examines Henry's actions and motivations in light of his circumstances, criticising when it is justified, but also giving credit where it is due. Overall he builds a picture of a Good and popular King, and talented commander, whose sense of justice, loyalty and duty could lead to excessive, and sometimes ruthless reactions against those who were disloyal to him. In context, this becomes more understandable, when it is shown that Henry was not born ti be King, and that his father's usurpation may have had a profound effect on the young Henry, making him more anxious to secure and protect his position, and maybe causing him to have a more extreme line on the importance of loyalty and obedience on the part of his subjects.
Allamand was one of the foremost experts on the Hundred Years war, and the rule of the Lancasrtians in France of his day, and so perhaps has more insight and knowledge of the reign of Henry, his legacy, and impact on history then most, if not all other biographers.
If you wish to truly understand Henry, read this book, it is not the easist read but is well worth the effort.