At the age of 18, having developed an interest in rocketry, Mansfield took up a job with the Rocket Propulsion Department of the Ministry of Supply in Westcott, Buckinghamshire.
Pada usia 18, setelah mengembangkan minat dalam bidang peroketan, Mansfield bekerja di Departemen Tenaga Penggerak Roket Kementerian Perbekalan di Westcott, Buckinghamshire.