It's not for want of trying that I haven't found anything Ron. The only written suggestion that I've seen of the PU 8/4 in BEF service was in Michael D. Taylor's old article about M/C recce units in which he says that 4 RNF appear to have had "Morris 8cwts (PU or PU 8/4)" - I don't know whether he was suggesting that it was both or simply that he didn't know.
They seem to have come on the scene a little late for BEF service but I'll keep looking.
