There are rather more obscure formula junior cars than I imagined .......................
Indeed. None of these cars are mentioned in familiar reference books - thus I could not provide extra information. Even race programmes don't state the make of engine fitted.
A Google search reveals that a Pierre Phillips still trades as a race preparation business in Portland, Oregon. Assuming he was a young man in 1961, thus born around 1940, it's feasible that this is one and the same person.
A point earned from persistency and knowing where to look.