On leaving university, he first worked in the electricity-generating industry, commissioning power stations in the UK and further afield. He joined Shell in 1990 working on drilling rigs and production platforms in the UK sector of the North Sea.

Mark joined the Corrib project in 2001 as the Operations Manager. In that role he has responsibility for recruiting the permanent staff who will operate the Corrib facilities, training the staff and ensuring all operating and maintenance plans are in place in advance of the start of gas production from Corrib. He will be responsible for the day-to-day running of the Bellanaboy terminal when it goes into operation.