How Much Is This Stamps ?!!

OK, the pattern is a single "F", it has repeated 4 times from the perf machine as it is regularily used to perf the smaller stamps (regular size difinitives) of the time period.
Without knowing what the actual measurement is, 7mm, 8mm, 9mm, etc (measure center of hole top to center of hole bottom), with same method across top of pattern.
In my old copy of "A Catalog of Great Britain Perfins" by Edwards and Lucas, the user
of those patterns were not listed at that time.I will have to try and find my updated listing.