The first child with well-differentiated thyroid cancer treated at the Royal Marsden Hospital presented in 1917. Since that time 30 children under the age of 16 years have been treated over a period during which many new treatments have been introduced. We have reviewed their management and outcome. The median follow-up is 22.5 years (range: 1-66). The median time to recurrence was 7 years (range: 2-44). There were events up to 44 years after presentation. The risk of recurrence was higher in children aged 10 years or younger [HR 3.45, 95% CI (1.04-11.11) P = 0.03]. Thyroid stimulating hormone (TSH) suppression was the only intervention to be shown to reduce the recurrence rate [HR 11, 95% CI (2.27-50) P = 0.0003]. The median overall survival is 53 years. The only presenting feature predictive of poorer survival was the presence of metastases (HR 28.96, 95% CI 2.51-334, P < 0.001). Patients who developed recurrence had a higher risk of death (HR 9.90, 95% CI 0.98-100, P = 0.02) and a shorter median survival of 30 years. No therapeutic intervention could be shown statistically to impact on survival. Our recommendation for treatment is total or near-total thyroidectomy for all patients and radioiodine ablation for all except those with early T stage node-negative disease aged over 10 years. Modified neck dissection is recommended for children with clinically positive neck nodes and TSH suppression for all. Follow-up with serial thyroglobulin measurement should be lifelong.