The Prince of Wales conducted a science experiment as he toured the factory of Notpla, in east London, which was awarded £1 million in funding from the Earthshot Prize.

Prince William said the advances made by the eco-packaging firm since it won the money last November are “breathtaking” and tried his hand at making his own seaweed membrane.

Notpla was awarded the funds after impressing judges with its biodegradable cartons made from seaweed.

The Earthshot Prize was established by William to find solutions to “repair” the planet.