Miranda is a non-executive director of Denver-based Liberty Global Inc (LGI), the leading international broadband cable group. She has worked with the Liberty group since 1988 and has built and managed international joint ventures on the company's behalf across Europe and Asia-Pacific.
Miranda was named President of Liberty Media International in 1999 and then assumed the title of President of Liberty Global Japan in 2005. In that capacity she served as the senior director of J:COM, Japan's largest broadband cable operator.
After leading the multi-billion dollar sale of Liberty's Japanese interests in 2010 she retired from her full-time executive role and accepted an invitation from Liberty's Chairman Dr John Malone to join LGI's board of directors.
Miranda is also a a Trustee of the Institute for Government, Deputy Chairman of Garsington Opera and Vice-Chairman of the leading African education charity Camfed.
In October 2011 she was named Chairman of Waterstones, and was nominated to the board of Marks & Spencer plc.