On a lot of the PHs I worked on, you could see where the "Made in Spain" stamp on the left side of the rear tang had been ground out.
PH may have used some German 98s early on, but I suspect that most of the converted military pattern actions were Spanish, as well as the commercial pattern actions.
As far as the commercial actions go, I have seen ones with the inner collar cut only for the extractor, inner collar cut on both sides, to ease manufacture, and no inner collar. Bolt variations as well, the last ones don't have the safety cam at the front of the firing pin. Last ones had the second rate bolt stops used on the Midland series. There are differences in the contour of the low scope bolt handles. PH .375 rifles used standard length 98 actions opened out for the much longer round. There are different opinions about how much steel can be removed from the back of the lower locking lug seat.
I do not know if PH rifles used Spanish barrels or not. The stocks are Sile, made in Italy.
Basically PH didn't make rifles in England, they assembled outsourced parts.
As far as I know, PH and commercial Santa Barbara actions were both made at LaCoruna Arsenal.