On the campaign trail he may have seemed subdued, but behind closed doors at the office Boris Johnson was back to being Boris yesterday.

Having been uncharacteristically sombre of late under the close watch of his media minders, the newly elected mayor could not resist making a series of quips during his first address to all City Hall staff. He himself, Mr Johnson reassured them, was no more a “crazed Thatcherite neocon” than his rival Ken Livingstone was a “Socialist who would hang the last 4x4 driver off the guts of the last non-dom”.

His door was always open, he said, and staff should address him by his first name “without fear of being fined £5 by Tessa Jowell”. Ms Jowell, who ran Labour's election campaign, threatened to fine colleagues who referred to Mr Johnson as Boris, in case it made voters see him as accessible and friendly.

Staffers who were at yesterday's meeting told The Times that Mr Johnson appeared jovial. “He wouldn't be Boris without the jokes,” one said.

It is understood that despite Mr Johnson's pledge to streamline the Greater London Authority and get rid of bureaucratic waste, redundancies and cutbacks were not mentioned.

Mr Johnson merely hinted at the issue, saying that he was elected to ensure that taxpayers received value for money, and that people would “inevitably leave” because of the changes to the administration.

One staffer said: “There were definitely some anxious faces. But I got the impression, when he said people would leave, that he simply wouldn't replace them, rather than sacking people. He said he wanted the majority of people to stay.”

Mr Johnson has already started replacing Mr Livingstone's political advisers and yesterday appointed Richard Barnes, leader of the Conservative Group in the London Assembly, as his overall deputy mayor.

The move could increase tensions with Sir Ian Blair, the Metropolitan Police Commissioner, as Mr Barnes has been one of his fiercest critics.

Sir Simon Milton, leader of Westminster City Council, announced yesterday that he would stand down to become a senior planning adviser to Mr Johnson. Sir Simon is expected to continue as chairman of the Local Government Association — which could raise questions over potential conflicts if he is to have a role in planning and development in the capital.

Mr Johnson is appointing several deputy mayors to provide advice on specific areas: his first was Ray Lewis, given the youth brief on Monday. Kit Malthouse, a Member of the London Assembly, will become deputy mayor of policing, and Ian Clement, the leader of Bexley council, will take on a role in government relations.

Mr Johnson played down talk of tensions in the handover at City Hall and promised to build on his predecessor's legacy. Visiting young people who were a fire safety course at an East London fire station, he said: “I am going to be talking to the staff later on, making a very simple point: the differences between me and the previous mayor have been greatly exaggerated.

“We do have differences in our political philosophies, but that does not mean there are not areas of common ground. I will do my best to work with the people at City Hall.”

Mr Johnson pledged that by the end of the week Londoners would see his priorities taking shape. He intends to bring in “respect schools” where troubled teenagers can attend weekend courses that combine sport and academic subjects.

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