The Druid’s Glen Hotel, nestled in the Wicklow Mountains, was a hive of activity last Saturday night as more than 120 alumni of the agribusiness Masstock gathered for dinner. It is 50 years since the business, started by the McGuckian family in Co Antrim, first went into Saudi Arabia in a ground-breaking move that brought Irish dairy to the hostile environment of the desert.  The impact of that 1976 investment was felt for decades afterwards, as thousands of Irish agricultural workers went to work for Masstock on huge dairy farms operated through a joint venture with its local partner, Almarai…