Your friend could either visit St. Catherine's House, or if she wished to start by investigating on-line I would suggest using either Find my Past, who detail BM & D's to 2006, or Ancestry.co uk, whose records can be searched up to 2005:
http://www.findmypast.co.uk/home.jsp
http://www.ancestry.co.uk/
Although these are not free websites, it will be quicker than trawling through the St. Catherine's records, and any relevant certificates can be ordered on-line.