Complex sentence: Brown stopped being a pilot when he turned 70, but he still lectures as of 2014 and is a regular attender of British Rocketry Oral History Programme (BROHP), where the annual presentation of the Sir Arthur Clarke Awards takes place.
Split into simpler sentences: Brown stopped being a pilot when he turned 70 but he still lectures. He is a regular attender of British Rocketry Oral History Programme (BROHP), where the annual presentation of the Sir Arthur Clarke Awards takes place.