A Welshman who "positively fizzes" with ideas and energy has become the country's top judge.
Referred to as a "moderniser" with a reforming spirit, Sir John took over the reins of the demanding role from Lord Judge, 72, who has retired after five years as head of the judiciary.
Around 300 people, including court staff and leading lights of the legal world - many clad in traditional dress of crimson and ermine or black gowns with gold braiding - packed the Lord Chief Justice's own impressive, wood panelled court at the Royal Courts of Justice for the occasion.
Congratulations were extended to Sir John on behalf of the Government, solicitors and barristers.
Welcoming him to the "very top job" that the judicial system of England and Wales has to offer, Lord Dyson, Master of the Rolls, said it was a "great day for Wales and also a great day for England".
Sir John, whose Welsh roots were of "enormous importance" to him, was known for his "prodigious energy", said Lord Dyson - describing him as someone who "positively fizzes with ideas" .
Justice Secretary and Lord Chancellor Chris Grayling said he was "delighted" by the appointment of Sir John.
He said the judiciary needed to be effective, independent and "one which is modern and moves with the times", adding: "We have someone in Sir John who is a moderniser. He has clearly demonstrated over the years a drive for constant improvement."
Upon Sir John's appointment, the Queen conferred a life peerage on him in "recognition of the contribution that he has made to law and justice reform".
He has previously described it as a "privilege and honour" to succeed Lord Judge, paying tribute to him for his "deep commitment to justice, the independence of the judiciary and the outstanding leadership he has given to all judges and magistrates".
Sir John, who has been p resident of the Queen's Bench Division since October 2011 - with recent high-profile cases including Abu Hamza and Julian Assange - has pledged that he will "endeavour to maintain confidence in the judiciary, its reputation and its high standards of integrity and impartiality".
Under the Constitutional Reform Act 2005, the work of a Lord Chief Justice involves around 400 duties which are required by law.
Key responsibilities include representing the views of the judiciary of England and Wales to Parliament and Government and sitting on important criminal, civil and family cases.
Lord Judge, who was born in Malta, studied at Cambridge and was called to the Bar in 1963.
A distinguished career followed, culminating in his appointment in October 2008 as Lord Chief Justice of England and Wales - at the same time being created a life peer as Baron Judge of Draycote in the County of Warwickshire.