Forbes was brought up on Craigmore Station in the South Island of New Zealand and worked as a shepherd in the early part of his career. He then trained in Agricultural Economics at Lincoln University in New Zealand where he was student president in 1984. He went to Oxford as a Rhodes Scholar in 1985. After some time at Goldman Sachs he completed an MBA at Harvard Business School in 1992. Forbes worked as a credit trader at Merrill Lynch from 1992 to 1999 where he headed a convertibles trading desk. He then led financial information publisher Credit Market Analysis which was acquired by Chicago Mercantile Exchange. Forbes returned full time to farming in 2005 to live on and manage Craigmore Station – a sheep, beef and deer property farmed by the Elworthy family since 1864.   From 2009 Forbes partnered with his brother-in-law Mark Cox to create Craigmore Sustainables, a specialist manager of farms and forests in New Zealand. Since 2014 he has been leading a Craigmore sponsored farm information management company called Map Of Agriculture. It provides software and farm data integration systems to help over 80 AgBusinesses including Centre for Dairy Excellence in New Zealand and McDonalds Restaurants in the UK connect to and assist their networks of farms.