Sir Richard's approach is perhaps best summed up by his reforming zeal.
And there is now press speculation that the 58-year-old, who was appointed in January 1998, could have to give evidence to the Hammond inquiry into the affair - which he set up on the orders of prime minister Tony Blair.
Sir Richard had lunch at the London home of the billionaire brothers, with Europe Minister Keith Vaz also present, in July 1998.
A spokeswoman for Sir Richard has insisted the issue of passports - which prompted the resignation of Peter Mandelson as Northern Ireland secretary - was "not discussed at all".
Prominent role
It is not the first time the spotlight has fallen on the present cabinet secretary, who is also head of the home civil service.
He has played a more prominent public role than many of his predecessors, including his immediate forerunner Lord Butler of Brockwell who served in the post from 1988, straddling the Thatcher, Major and Blair premierships.
Sir Richard represents the new breed of executive-style, management-orientated civil servant.
It is a world away from the role personified by cabinet secretary Sir Humphrey Appleby in the comedy series Yes, Prime Minister.
Sir Richard's approach is perhaps best summed up by his reforming zeal.
In 1999 he announced plans to attract more women and people from ethnic minorities into the civil service.
It was part of a wider package of change, including a drive to reduce bureaucracy, all aimed at creating a more modern, open organisation.
But Sir Richard's role in previous government controversies has also caught public attention.
In February 2001 he reprimanded Alastair Campbell, the Prime Minister's official spokesman, over comments deriding Tory economic policy as an insult to Mickey Mouse.
But the civil service chief ignored calls from opposition parties to force the Number 10 press spokesman's resignation.
Sir Richard had previously said that, although Mr Campbell can place government policy in a political context in a way career civil servants cannot, he was not entitled to attack the opposition with "bricks and bottles".
Inquiry head
Last year Sir Richard was given the task of finding out who leaked a government memo in which Tony Blair spoke of fears the government was regarded as "out of touch" on issues such as crime and asylum-seekers.
The Welsh-born career civil servant went to Radley public school and studied law at Cambridge University.
His rise started at the then Board of Trade and took in departments including the Cabinet Office, Treasury, Environment and Home Office - where he was permanent secretary from 1994 to 1997.
He is married with two children and lists his personal interests as gardening and cinema.