After qualifying as a Chartered Accountant in 1968, Mark worked at the BBC for 10 years. He then moved to the RSPCA as its chief accountant. In 1981 he became Chief Finance Officer and in 2008 Chief Executive. His role at the RSPCA included membership of the Board of World Animal Protection. Following his retirement in late 2012 Mark continued as a WAP Board member becoming its chair in 2014 until 2018. Since that time Mark has been an honorary member of CIWF audit and finance committees.