Julian joined the Atlas Computer Laboratory in 1970 working on computer graphics.
He became a member of RAL in 1975 when the two laboratories merged and stayed there until his retirement in April 2008. His roles at RAL included group leader; national programme coordinator; standardization expert; developer and researcher. He worked on distributed computing, Grids, visualization, computer graphics, data mining, data modelling, data representation, technologies for learning and Internet tools for collaboration. He co-authored two books, and co-edited another. At the end of his career, he worked as team leader, senior researcher and work package leader on European and UK R&D projects including Akogrimo (Grids, mobility, standardization), ELEGI (Grids, learning), Telemac (data mining), XtreemOS (operating system for Grids), gViz (Grids, visualization) and MOB (product data).
In 2013 he was a Tutor at Oxford University Department of Continuing Education and an independent ICT contractor.