Respected lawyer Sir Peter Williams QC will be farewelled in Auckland this afternoon.

The criminal lawyer and prisoner rights advocate was battling prostate cancer for a decade and died in his Auckland home on Tuesday, surrounded by family.

He will be farewelled at the Holy Trinity Cathedral in Parnell at 1pm.

Williams was involved in more than 100 criminal trials in his 60-year career in the justice system - often fighting on the side of the underdog which won him much respect.

He also took part in high-profile cases including Terry 'Mr Asia' Clark and Bassett Road machine gunner Ronald Jorgensen.

He represented Arthur Allan Thomas at the Royal Commission that cleared him of the murders of Harvey and Jeannette Crewe in 1971.

Sir Peter founded the Criminal Bar Association, and led the Howard League for Penal Reform.

Sir Peter received his official knighthood in April this year at special ceremony at his home - brought forward from the official date due to ill health.

He is survived by wife Lady Heeni Phillips-Williams, children Cara, Durell and Paula, Katie and Clint, and grandfather of Scarlett, Conor, Grace, Toby, Plum, Iris, and Rory.