A QC who co-founded Cherie Blair's legal chambers has been named new head of the Crown Prosecution Service amid allegations of "rampant cronyism".
Mr Macdonald is taking on a difficult job
Ken Macdonald will take up the post in autumn when the current director of public prosecutions Sir David Calvert-Smith retires.
But the Conservatives' shadow deputy prime minister David Davis said the appointment of someone who worked with the prime minister's wife was "astonishing".
Mr Macdonald has practised criminal law for 25 years and is a founder member of Matrix Chambers, where Mrs Blair works.
His experience of criminal cases is said to range from domestic and international terrorism to city fraud, gangland violence, child abuse and money laundering.
He was appointed by a panel made up of two senior civil servants and a senior judge, under the chairmanship of the First Civil Service Commissioner Baroness Usha Prashar.
There had been adverts in national newspapers for the £145,000 a year post.
Mr Macdonald said: "I agree with the Attorney General and Sir David Calvert-Smith, the
present DPP, that it is time for prosecutors to take their proper place at the heart of criminal justice.
"A transparent, fair and effective prosecuting authority is one of the hallmarks of a great liberal democracy. This is our aim."
But Mr Davis said the appointment was not appropriate.
"Many people will find this appointment astonishing.
"We have already had one Lord Chancellor who was the prime minister's boss
and the current one who is his former flatmate.
"Now we learn that the new director of public prosecutions is a founder member of the same legal chambers as the prime minister's wife.
"Under this government there appears to be no institution which is safe from
the prime minister's rampant cronyism."
Liberal Democrat home affairs spokesman Simon Hughes said: "I have no reason
to doubt that Ken MacDonald is up to the job, but this is a provocative appointment.
"This is becoming more and more a government of who you know rather than what you know.
"Whether or not it is intended, jobs increasingly appear to go to people who
are 'one of us'."
Sir David hit the headlines recently when he defended the CPS's pursuit of expensive failed cases against mother Trupti Patel and Royal butler Paul Burrell.
Mr Macdonald - who lives in London with his wife and three children - is chairman of the Criminal Bar Association and has also held a number of positions on the Bar Council.
Since 2001, the 50-year-old has been a part-time judge in the Crown Court.
Having been counsel in a number of major fraud trials, he opposed government moves to hold some fraud cases without a jury.
There had been speculation in at least one newspaper prior to the announcement that a number of black candidates might be in the running.
But Mr Macdonald fits the more traditional profile of DPPs, a middle class, white, Oxford-educated male.
Indeed his four predecessors were all Oxbridge-educated.
Mr Macdonald lists his interests in Who's Who as 20th century history, crime fiction, film noir and supporting Arsenal.