The coins are currently made from the nickel and copper alloy cupro-nickel.

BBC: Treasury 'should foot coin change bill'

The use of maillechort, a tarnish-resistant, creamily beautiful but easily marred alloy of copper, zinc and nickel, sometimes also called "German silver, " for the plates and bridges is a case in point.

FORBES: It's About Time

The Treasury plans to make the new coins from nickel-plated steel instead of the alloy, which has become more expensive as the price of copper has risen in recent years.

BBC: Treasury 'should foot coin change bill'