I never actually 'owned' one but did use them for special jobs......
It was designed and made by a remarkable man,...a Mr Corfield. Everything designed by him was ingenious,.....If I remember correctly, he eventually became Sir David Corfield...(?)
I don't think the Periflex was really intended for use by amateur users,.....it was used a lot in UK industry/armed forces particularly as an oscilloscope and microscope camera and I think(?) it was actually designed with this in mind. At the end of WWII the UK aquired the plant and spare parts to make the pre-war Leica,...they were assembled by a UK aeronautical company called Reid and Sigrist and the main reason was to keep the RAF and some other top line UK aircraft research groups suplied with oscilloscope cameras. After a while, Reid & Sigrist saw the commercial possibilities and sold the r/f version as the 'Reid 2'.......Corfield attempted to supply the technical requirement for an instrument camera much more cost effectively.