As might be expected, I discovered that US affiliates were not as productive as
their parent companies, but were more productive than their local competitors. This
then suggested that, in the 1950s, at least, Anglo±American productivity differences were partly explainable by location (L) and partly by ownership (O) specific
characteristics. However, my study omitted to ask a folow-up question, namely, to
what extent was the origin of the O advantages of US firms themselves home
country specific? Neither did it attempt to distinguish between those O advantages
that arose as a consequence of US direct investment in the UK, and those that the US
firms possessed prior to engaging in foreign production.