The article didn't admit this directly, but the study they linked to found the average height of British 5-year-olds was lower than that of mainland China, Cuba, or North Korea for both genders: https://ncdrisc.org/height-mean-ranking.html (Keep in mind they found 5-year-old Cuban girls were taller than 5-year old American girls, and that North Koreans are taller than either Chinese or South Korean girls of that age, so I don't know what to make of the data - tall kids don't necessarily grow into tall adults, but there does seem to be some nutritional stunting going on.)

https://www.theguardian.com/business/2023/jun/21/children-raised-under-uk-austerity-shorter-than-european-peers-study