A handout picture released by the British Royal Mint

Britain’s new £1 coin with the symbols of England, Scotland, Wales and Northern Ireland goes into circulation from Tuesday on the eve of the launch of a Brexit process that has put national unity in doubt.

The 12-sided coin is the first change to the shape of the £1 coin since its introduction in 1983. Britain’s finance ministry said the new coin would be “the most secure of its kind in the world” to prevent a rise in counterfeits. About three percent of the current round-shaped coins are fakes.

The new pound coins will be thinner, lighter and slightly bigger than the old ones and will have a hologram-like image that changes from a “£” symbol to the number “1” when viewed from different angles.

“Staying ahead of sophisticated counterfeiters remains a constant challenge and this coin helps in that battle,” said Adam Lawrence, head of the Royal Mint, which is producing around 1.5 billion new coins.

The new bi-metallic coin has the same shape as the popular old “Threepenny bit” that was introduced in 1937 and went out with decimalisation in 1971.

Queen Elizabeth II’s portrait will be on the obverse side of the coin, while England’s rose, Scotland’s thistle, Wales’s leek and Northern Ireland’s shamrock will be on the other side, held in a crown.

The old coins cease to be legal tender on October 15.

Prime Minister Theresa May on Wednesday is set to formally notify the European Union of Britain’s intention to leave the bloc in a process that has caused a steep plunge in the value of the pound compared to the euro and dollar.

The United Kingdom as a whole voted to leave the EU in a referendum last year.

Most voters in Scotland and Northern Ireland wanted the UK to stay in the EU, but a majority in England and Wales opted for Britain to leave the bloc.

Britain’s new pound coin