He worked there as a photographer and assistant sound engineer.
[1] During the Second World War, Leeston-Smith was part of the Royal Horse Artillery.
In 1953, he took a job as a sound engineer on the BBC Television serial The Quatermass Experiment and two years later was a production assistant on the sequel, Quatermass II.
He directed a number of episodes of Z-Cars, R3 and the Doctor Who serial The Myth Makers.
[2] After a period as a freelance director, Leeston-Smith moved to South Africa in 1973 to work for the SABC when it was starting up its television broadcasts.