Background/objectives: The use of simple screening tools to measure nutritional adequacy in a public health context in developed countries are currently lacking. We explore the relationship between food variety and nutrient intake of London school children using a simple tool with potential use for screening for inadequate diets. Subjects/methods: A cross-sectional survey was carried out in 2010. The survey included 2579 children aged 7−10 years in 52 primary schools in East London in the United Kingdom. The analysis included 2392 children (93% of the original sample). Food variety was assessed as the total number of listed foods recorded over 24 h using the validated Child and Diet Assessment Tool (CADET) comprising 115 listed foods divided into 16 food categories. Dietary quality was determined by the proportion of children meeting recommended intakes of individual micronutrients, namely, calcium, iron, zinc, folate, vitamin A and vitamin C. Results: The mean number of CADET-listed foods consumed daily by children was 17.1 (95% CI: 16.8, 17.5). Children who consumed fewer than 11 foods on the collection day had particularly low nutrient intakes. Children consuming three different vegetables and two different fruits on average consumed 19–20 listed foods. It was estimated between 4 and 20% of children did not meet the recommended levels for individual micronutrients during the period of data collection. Conclusions: A simple method using food counts to assess daily food variety may help public health nutritionists identify groups of children at risk of inadequate diets.