Master May was called to the Bar in 1967, took silk in 1979 and became a Recorder in 1985. He was appointed to the Queen's Bench Division in 1991 and appointed to the Court of Appeal in 1997. Master May was Vice-President of the Queen's Bench Division from 2002 to 2008, Deputy Head of Civil Justice 2000 to 2003 and a member of the Civil Procedure Rule Committee (2000-03). He was the President of the Queen’s Bench Division from 2008 until his retirement in July 2011. He served as the Interception of Communications Commissioner between 2013-2015

Master May was elected as a Bencher of the Inn in 1985 and served as Treasurer in 2008, during which year Inner and Middle Temple celebrated the 400th Anniversary of the Letters Patent of James I which conveyed the lands and buildings of the Temple to the two Inns in free and common socage. These letters patent confirmed the Societies' status and defined purpose. On 24 June 2008, Her Majesty Queen Elizabth II presented the Inns with a confirmation of their 1608 letters patent, a copy of which is hung outside the Parliament Chamber. To celebrate, a year long Temple Festival was held which included an Open Weekend that saw nearly 25,000 visitors to the Inns and a variety of events including public music performances, two major public debate series, the inauguration of The Inner Temple Book Prize and the installation of the 400th anniversary stained glass window in the Temple Church. Master May also oversaw the final negotiations between the Inn and the Apex Hotel resulting in a long lease of Serjeants' Inn which has provided financial security for the Inn to continue developing and improving its estate. 

Master May, with former Treasurer of Middle Temple, Michael Blair KC, chaired the highly successful Temple Church Organ Appeal. Thanks to the enormous generosity of Benchers and members of both Inns, the appeal raised sufficient funds to restore the Harrison & Harrison organ, donated by Lord Glentanar after the War to replace the 1680 'Father Smith' organ that had been completely destroyed during the Blitz. The appeal culminated in a service of rededication of the Temple Church Organ on 7 May 2013 in the presence of Her Majesty The Late Queen Elizabeth II and former Royal Bencher, His Royal Highness The Duke of Edinburgh. 

The Inn's flag will fly at half-mast in his memory on Monday 13 January 2025. A private funeral service is being held and a memorial service will be held in the Temple Church later in the year. Lady (Stella) May, their three children, Charmian, Lavinia and Richard and nine grandchildren survive him.