Gordon Brown has begun the process of governing and has held discussions with major foreign leaders.
The prime minister was on Wednesday afternoon applauded by Number 10 staff as he entered his new place of work.
He held a meeting with cabinet secretary Sir Gus O'Donnell, and immediately revoked the Orders in Council which had allowed special advisers to instruct civil servants.
Brown also had a 10-minute phone conversation with President Bush which was described by the prime minister's spokesman as "an introductory call that was business-like and constructive".
The prime minister has also spoken to French president Nicolas Sarkozy, German chancellor Angela Merkel, Italian prime minister Romano Prodi and Irish premier Bertie Ahern.
There was also a "courteous and business-like" conversation with Conservative leader David Cameron and a separate discussion with Liberal Democrat leader Sir Menzies Campbell.
It was also announced that Brown will continue to appear before the Commons liaison committee of senior MPs and will hold regular press conferences.
The public petitions section of the Number 10 website will also be maintained.
