Devonshire’s youngest son was diagnosed with coeliac disease aged two. She said: “I was absolutely thrilled to be asked to be an ambassador for Coeliac UK because raising awareness of coeliac disease especially for children, is a cause close to my heart.

“I’ve seen first-hand the difference that early diagnosis can make and I want to help the charity reach more parents and carers who might be struggling and searching, sometimes for many years, to find answers to their child’s ill health.”

Symptoms of undiagnosed coeliac disease in children include diarrhoea, unexpected weight loss, a bloated tummy, faltering growth and dental enamel defects.

Coeliac UK is aiming to reduce the average diagnosis time of 13 years. Having coeliac disease can lead serious health problems in later life including anaemia, unexplained infertility and an increased risk of small bowel cancer.

Coeliac is an autoimmune disease where the body’s immune system damages the lining of the small bowel when gluten is eaten. One in every 100 people in the UK suffers from the disease but only 30% are diagnosed. There is no cure for coeliac disease but it can be managed by keeping to a strict gluten free diet.

Hilary Croft, chief executive of Coeliac UK, added: “We are delighted to welcome Jane as our new ambassador. She has always been a great friend to the charity and is the perfect person to rally support around our children’s campaign in 2020.

“With her help, we hope to increase diagnosis rates by encouraging all parents, grandparents or carers who are seeing symptoms like faltering growth, unexpected weight loss or a bloated tummy in their child to go to their GP and ask for a blood test for coeliac disease.”

Coeliac UK Awareness Week is due to take place from 11-17 May 2020.