In 1987 the UN Secretary General appointed Mr. Ndegwa to a panel of international economic experts charged with analyzing Africa's debt crisis and proposing policies to address it.  Mr. Ndegwa also worked with the UN Environmental Programme and rose to become its assistant director.

Mr. Ndegwa wrote a number of books on economics and politics in Kenya and Africa.  His last book, coauthored with Mr. Reginald Herbold Green and published in 1994, is Africa to 2000: Imperative Political and Economic Agenda.  This book calls for depoliticizing the allocation of development resources in Kenya, eliminating high level corruption, and allowing greater freedom for the media.  He was a research fellow and lecturer in economics at Makerere University and authored leading works on economic trends in Africa.

In addition to assuming the role of Chairman of Kenyan Airways in April 1991, Mr. Ndegwa served as Chairman of the Kenyan Revenue Authority, First Chartered Securities Limited, The Society for International Development, Kenya Chapter, the Insurance Company of East Africa (ICEA) and the African Mercantile Bank.
 
Philip Ndegwa died on 7 January, 1996.  President Moi expressed his sorrow and shock, and sent condolences to Ndegwa's family.  Finance Minister Musalia Mudavadi noted, "The late Ndegwa leaves behind an impeccable record of public service and particularly in the economic management of our nation."   Mr. Ndegwa played a crucial role in the restructuring and privatization of Kenya Airways.  He lived just long enough to see Kenya Airways successfully attract a strategic investor, a key step in his plan to rebuild Kenya Airways as a viable, commercial enterprise.