Short answers, pulled from the story.
William Brereton, born approximately 1487-1490, was a member of a prominent Cheshire family who served as a groom of the privy chamber to Henry VIII. He held numerous royal offices across Cheshire and the Welsh Marches and accumulated an annual income of more than ten thousand pounds, making him one of the wealthiest men at the Tudor court.
Brereton was accused of committing adultery with Anne Boleyn and executed for treason on the 17th of May 1536. Historian Eric Ives argues that Thomas Cromwell added Brereton to the plot against Anne primarily to end Brereton's control of the Welsh Marches and centralise that region's government, not because of genuine evidence of adultery.
Yes. Brereton pleaded not guilty at his trial, maintained his innocence to individuals he spoke with, and his final words on the scaffold were a carefully worded statement that most historians read as a cautious declaration of innocence. Eyewitness George Constantine wrote after the execution that if any of the condemned men were innocent, it was Brereton.
Brereton held a wide range of positions simultaneously, including groom of the privy chamber, Escheator of the county palatine, sheriff of Merioneth and Flint, constable of Chester Castle, ranger of Delamere Forest, and Chamberlain of Chester, among many others. The 1526 Eltham Ordinances confirm him as one of only four grooms of the privy chamber.
Brereton delivered jewels to Anne Boleyn in 1531 on Henry VIII's orders, and he was one of a small number of witnesses at Henry and Anne's private wedding in January 1533. Historians note there is no indication he had a close or intimate personal relationship with the queen, and the accusation of adultery is now widely considered false.
Brereton was played by Brook Williams in the 1969 film Anne of the Thousand Days, by Mark York in the 1972 film Henry VIII and His Six Wives, and by Scottish actor Alastair Mackenzie in the 2015 television adaptation of Hilary Mantel's Wolf Hall. His most inaccurate portrayal was in the Showtime series The Tudors, where he was depicted as a young Jesuit, a description the sources call entirely fabricated.