In 1994, he was appointed chairman of the Equal Treatment Advisory Committee of the Judicial College.

In 1998, he became presiding judge of the Technology and Construction Court, a specialist part of the Queen's Bench Division.

[6] It was announced in December 2010 that, by Royal Warrant, all members of the Supreme Court, even if they did not hold a peerage, were entitled to the judicial courtesy title of "Lord" for life.

[9] In the event, Dyson was appointed Master of the Rolls with effect from 1 October 2012[10] as was widely expected following the announcement of Neuberger's appointment (also with effect from 1 October) as President of the Supreme Court of the United Kingdom in July 2012.

[11][12] From 2012 to 2016, he was Chairman of the Magna Carta Trust and of the Advisory Council to the Secretary of State for Culture, Media and Sport on National Records and Archives.

[13] Dyson retired and was replaced by Sir Terence Etherton as Master of the Rolls on 3 October 2016.

[15] In a study published in 2024, he is recorded as openly critical of Lord Hope of Craighead in publishing Diaries revealing Lord Hope's account of judicial panel deliberations and confidential conversations between judges.