|“||Outspoken honesty was not a virtue generally prized in a valet, but it was a virtue for all that—and Grey prized it.||”|
Tom Byrd is a boot boy in Mr. Trevelyan’s household. After his brother Jack's mysterious disappearance, he tells Lord John that Mr. Trevelyan sent him to be of assistance.
Tom accompanies Lord John to the viewing of the body of Sergeant O'Connell, and summons the constables when two mourners nearly come to blows.
Though Lord John later discovers that Tom Byrd has bluffed his way into the position and left without Trevelyan's knowledge, Lord John elects to keep Tom on, having found him an adept assistant and valet.
For his part, Tom quickly becomes devoted to Lord John. When Lord John is poisoned, Tom defends him tenaciously and does his best to help him recover.
Tom accompanies Lord John to Prussia. He is unnerved by the stories of ghosts and succubuses, though he gamely assists Lord John. Lord John tasks him with speaking to the servants, and Tom tells Lord John about St. Orgevald and the circumstances surrounding Siegfried's birth.
Tom accompanies Lord John to Helwater, and tells Lord John the servants' version of Geneva Dunsany's death.
Tom later accompanies Lord John to the Rhine Valley, where Lord John is stationed with the 46th Foot. When Lord John is injured by a cannon at Crefield, Tom dotes upon him and fiercely protects him. Even after their return two months later, Tom is greatly concerned for Lord John, and insists that he rest as much as possible.
Tom meets Lord John after his testimony at the inquiry. He is later present for Mr. Lister's account of his son's elopement. When Mr. Lister seems to see his son Phillip's death on the battlefield as one of ignominy rather than honor. Tom tells Lister that if it weren't for war (and soldiers), "you'd be saying what you just said in bleedin’ French, wouldn’t you?” 
Lord John hastily sends Tom away, but agrees with the sentiment if not the manner of expression.
As Lord John's investigations into Phillip Lister's death continue, Tom gossips with locals and reports that Captain Fanshawe was severely injured in an explosion. Upon their return to London, Tom talks to a pawnbroker who remembers a man named Fanshawe pawning some of Phillip Lister's former sweetheart's jewels. Tom proves invaluable once again when he tells Lord John that he noticed Herbert Gormley being press-ganged.
Tom accompanies Lord John when he travels to Canada to testify on behalf of Charlie Carruthers.
Tom is terrified of Lord John's long-time friend Jamie Fraser. When the latter stays at Argus House for a time, Tom does his best to face his fears and begins to feel more comfortable around Jamie. Tom takes personal responsibility for ensuring that Jamie looks the part of a gentleman rather than a groom. Tom becomes even more comfortable around Jamie after seeing him violently seasick on their journey to Ireland. After Jamie is attacked by Gerald Siverly, Tom tends his wounds.
When John Grey is arrested for the supposed murder of Gerald Siverly, Tom works with Jamie to help John escape.
Tom is unnerved by the fauna of Jamaica, but does his best to help Lord John Grey unravel the mystery. Tom is later kidnapped by the maroons, and Lord John is forced to rescue him. Tom, though frightened, tells Lord John that he was sure Lord John would be "right along" to rescue him.
Tom accompanies Lord John to Cuba. Lord John later sends him on a dangerous mission to find George Stanley behind the English lines.
Tom extremely loyal to Lord John. He is fastidious with Lord John's appearance, frequently rebuking him for dirtying his clothes.
Tom is short and stocky with brown hair, freckles, a snub nose, and "a head as wide as a cannonball." When Lord John first meets him in 1757, he's about Lord John's own height (approximately 5'6"). By the time he's twenty-one, however, he's grown several inches and become "nicely muscled."
- Tom is a short form for Thomas, which derives from the Greek form of the Aramaic name תָּאוֹמָא (Ta'oma') which meant "twin".
- Byrd as a surname is a variant of Bird, which was an occupational name for a person who raised or hunted birds.
- Tom Byrd appears in every Lord John book with the exception of Lord John and the Hellfire Club.
- In his later years, John remarks that Tom was the best valet he ever had.