A new £1 coin, billed by the Royal Mint as the "most secure coin in the world", is set to be introduced in 2017.
The 12-sided coin was designed on the old threepenny bit, and comes in the same gold and silver colours as the euro.
It will replace the current coin, which has been in circulation for thirty years and has become vulnerable to sophisticated counterfitters.
Chancellor George Osbourne took a two-coloured prototype to Buckingham Palace on Tuesday evening to show to the Queen.
On Wednesday, he delivered his fifth Budget to MPs in the House of Commons.
Mr Osbourne tweeted a picture of the £1 coin next to the Budget Box, captioned, "Today I will deliver a Budget for a resilient economy — starting with a resilient pound coin."
The current £1 coin was introduced in 1983 as part of the phasing-out of the £1 note.
The Royal Mint estimates that about 45 million £1 coins in circulation are now forgeries.
As with all British coins, the Queen's effigy will appear on the 'heads side'.
There will be a public competition to decide the design for the 'tails side' of the coin.
Photo: © Rex