Portillo was born in Bushey, Hertfordshire to an exiled Spanish republican father, Luis Gabriel Portillo (1907-1993)[REF] and a Scottish mother, Cora (née Blyth) (1919-2014), whose father John Blyth was a prosperous linen mill owner from Kirkcaldy [REF].
Portillo graduated in 1975 with a first-class degree in history, and after a brief stint with Ocean Transport and Trading Ltd., a shipping and transport company, he joined the Conservative Research Department in 1976.