'Business as usual, mixed with grief' will be the local government mantra after the Queen or another senior public figure dies, it has been revealed.

Mayors will issue 'sympathetic' messages, council websites will feature pictures of the deceased and a national period of mourning will be declared upon the death of the monarch.

The advice is part of a document issued to councils which is on the agenda of a Swaffham Town Council meeting next week.

The code name of the plan to manage the government response to the Queen's death is called Operation London Bridge, and it has been in development since the 1960s.

The phrase 'London Bridge is down' will be used to convey news of the monarch's passing at the highest levels, triggering 10 days of mourning.

Documents issued to the town council say the Queen's successor will be proclaimed on the first day after she dies, with civic services to take place the following Sunday, and her funeral planned for the 10th day.

Whoever holds the title of Duke of Norfolk has overseen royal funerals since 1672. Since 2002, the duke has been Edward William Fitzalan-Howard.

Councils have been advised to wear black arm bands, rosettes and even 'mourning bags' at official meetings and events, and should respect the 'mood of the nation' at what will undoubtedly be a turbulent time.

Bullet points for councils to follow include: 'business as usual, mixed with grief', 'instigate your action plan' and 'public holiday'.

Plans for the deaths of other senior royals are similarly named - Prince Philip's plan is called Forth Bridge, Prince Charles's is Menai Bridge and the Queen Mother's was Tay Bridge. The plan for Winston Churchill's death took the rather more wistful title, Hope Not.

Plans have even been drawn up for what to do depending on where the Queen is when she dies.

If she is at Sandringham, her body will be moved by car to Buckingham Palace within a couple of days.