Ministers have been accused of criminalising the flying of the European Union flag on government buildings in England after London's City Hall was told it could be prosecuted for displaying it on the anniversary of the Brexit referendum.
Seven years after the referendum on leaving the EU, the Greater London authority (GLA) had planned to fly the flag on Friday but officials were advised that under the latest regulations they would need to secure permission from the local authority.
Without so-called advertising consent from Newham council, City Hall, which is the headquarters of the GLA and is where Sadiq Khan, the capital's mayor, is based, would have been liable to criminal prosecution under the amended town and country planning (control of advertisements) regulations.
There is no such consent required for flying the flag of any country in England.
Also exempt are the flags representing the Commonwealth, the United Nations, sports clubs, the NHS, specified award schemes such as eco-schools and the rainbow flag of six horizontal equal stripes of red, orange, yellow, green, blue and violet.
Until 2021 the EU flag had also been among those that did not require permission but the law applying to England was changed as a response to the UK's departure from the bloc on 31 January 2020.
Encouragement was instead issued by ministers at the time to fly the union flag of the UK throughout the year on national government and local authority buildings.
Khan will instead use lights to display the EU flag's blue and yellow colours on the building to mark the anniversary of the Brexit vote.
A City Hall source said: "The mayor is proud to fly flags from City Hall - from the Union flag to the Ukraine flag in recent times. Flying a flag is a way of showing solidarity, expressing our values, and showing pride in the identities we share.
"With over a million people calling London their home from other European countries it's extraordinary that the government has effectively banned the European flag being flown without going through a long and bureaucratic planning process.
"Europeans contribute hugely to our social and economic life, and all we wanted to do was show our gratitude with a small gesture for one day of the year."
On a 69.7% turnout, 59.9% of Londoners who voted on 23 June 2016 wanted to remain in the EU, compared with 40.1% who voted to leave.
Seven of the 10 areas with the highest share of the vote for remain were in London, including Hackney, Lambeth and Haringey, where more than 75% of votes were to stay in the bloc.
In an open letter to Londoners from one of the 27 EU member states to mark the anniversary of the referendum, Khan writes: "Seven years ago today our country voted to leave the European Union. It was a heartbreaking day for me, and I know it was for many of you too.
"There is no doubt that in the years since, Brexit has caused huge damage to our city and created a great deal of uncertainty for many of you. But you stayed with us.
"Despite the appalling uncertainty over settled status, despite being used as bargaining chips in the negotiations and despite the antimigrant rhetoric coming from this government, you kept the faith and continued to make London your home."
Khan wrote that he would also back the call from Keir Starmer, the Labour leader, for EU citizens who live and pay tax in the UK to have the right to vote in general elections. The prospect could enfranchise about 5 million EU citizens over the age of 18 living in the UK with settled status.
The Department for Levelling Up, Housing and Communities declined to comment.