I just emailed a club memebr who has a Prefect. here is his reply
Regarding the floor rubber for late '30s, '40s, and pre '53 Prefects, the Side Valve Club in England may have 'repopped' the mats. They were and are a fairly active Ford group in the UK. As an alternative, if visual reference is available, the mats can be fabricated quite successfully using appropriate rubber floor mat textures available from restoration sources or companies such as Spaenaur in Kitchener (about two blocks further west of the pub location). Cut out shapes and grooves, ribs, etc. can be contact cemented to a thin rubber backing. A layer of 'horsehair' or felt can be also glued under the fabricated mat for effective sound deadening. I have used the process and it works! My '49 Crosley mats, both front and rear, are made as such. My '59 Prefect has a fresh, period correct, textured rubber mat that is continuous from front to rear with small grooved individual mats sitting on top. It appears typical if not prototypical. Perhaps, if and when I find excellent reference or a scrapper original mat, I will then make a weekend project of building a visually correct mat replacement. Until then, because I have never had the pleasure of parking beside a row of restored 100E Anglias or Prefects, it hasn't become an issue.