I might be onto something here I reckon. My little X-Planes book by Jim Winchester has turned up the HANDLEY PAGE HP115. Anigrand have made it in kit form - below - looking very PF1'ish with its strikingly similar sweeping delta wings this time done as a single triangle of plastic.
And here's a model (wooden?) currently on Ebay by myasainart. If we could add the antenna'd tailfin of the BAC 221 we would have a sort of Probe Force 1 maybe? Just those pesky exhausts to find now!