The union flag is flying at Belfast City Hall on Wednesday for the first time since a decision not to display it permanently sparked protests, some of which have been violent. The move marks the Duchess of Cambridge’s 31st birthday, BBC informs. Police were attacked with petrol bombs and fireworks for a sixth night in east Belfast on Tuesday. The cost of policing flag protests in Northern Ireland since they began early in December is believed to be over £7m.A campaign of street demonstrations started just over a month ago, when Belfast councillors voted on 3 December to limit the days when the union flag flies over Belfast City Hall. Some of the protests have been violent and resulted in more than 100 people being arrested and dozens of police officers sustaining injuries.The flag was raised on Wednesday to mark the Duchess of Cambridge’s birthday, but will be taken down again in the evening and loyalists have made it clear they will continue their protests.Their central demand is for the decision to be reversed but the political make up of the council means there is little chance of that happening. It has been confirmed that the cost of policing the flag protests and dealing with disorder during the first two weeks from 3 to 17 December was £3.8m. On Tuesday night, petrol bombs, bricks and bottles were thrown by loyalists in Templemore Avenue, off the Lower Newtownards Road. Secretary of State Theresa Villiers has said Northern Ireland was being “held to ransom by protesters”, and she called for an end to all street demonstrations over flags, even peaceful ones.