Waitrose has launched a customer competition to celebrate the 25th anniversary of the organic food brand Duchy Originals.

The retailer is inviting customers to submit their ideas for a main course featuring the organic brand’s ingredients, which is only sold in Waitrose.

The winner will be invited to a celebratory banquet at Dumfries House in Ayrshire, Scotland, where the winning dish will be served at a dinner hosted by The Prince of Wales.

The brand was created by the Prince to encourage organic farming, and has exceeded £200m in sales for the first time.

Rob Collins, managing director of Waitrose, said the 25th anniversary highlighted the extraordinary vision of The Prince of Wales.

“In creating the Duchy brand, he has encouraged more sustainable agriculture and expanded the market for organic food in the UK and around the world,” Collins said. “We are honoured to be the custodians of the brand and delighted to have achieved the significant milestone of £200m in annual sales.”

The current range of Waitrose Duchy Organics available in the UK has grown to 300 products, from biscuits to vegetables.