"Charles Ellson" wrote

BoE notes have holograms integrated into the (made from rag IIRC)
paper so mixing materials doesn't seem to be a problem. With Braille I
suspect the difficulty lies with the inconstant thickness resulting or
the eventual flattening of the "dots". Punching holes in the notes is
probably not an option so relying on textural differences seems to be
the remaining option if the size and/or colour can't be changed.
Possibly a variation on the BoE holograms could provide textural
"dots" but how many different denominations of dollar note would need
to be identified ?

I'm not sure what features blind people use to distinguish BoE notes, but
apart from different size for different denominations, and the hologram,
they use raised printing. In the past the size of BoE notes have changed
(the white fivers were ginormous, and in the 1960s we got new small pound
notes - didn't we accuse Harold Wilson of shrinking the pound?), though I
suspect that changing the size of notes now would cause difficulties for
cash machines, vending machines that accept notes, etc.

Peter