Mystery Blade - Fazakerley?

Can anyone identify the source of this Enfield foresight blade. Although it is not visible in the photos, as I do not have adequate equipment for making macros, if you turn it around there is a rather high-set point (.) in front of the 09. It definitely is an 0.09 - I compared it with other marked blades.

Attachment 47520

The marking above appears to be a WD arrow joined to an "F". Once again, moving it around reveals no trace of a bottom stroke to make it a possible "E".

Fazakerley, or an external supplier?

.090 is from a Sten Gun and I'd say that as Fazakerley were prolific Mk5 Sten gun manufacturers, it'll be an F

Thanks Peter! It's going onto a No1, to provide some leeway in height adjustment for 100m shooting.

That's interesting Patrick.......... Because after the war, it was found that some No4's, for reasons not quite fathomable, could only be zeroed by using the .090" Sten foresight so after a series of trials the slightly higher 'H' marked foresight block band was introduced. This meant that............... Anyway, I wrote a long paper on the foresights and the post war foresight block bands, including the 'H' marked ones that very few people know/knew about.

Maybe someone of a more computer literate bent could resurrect it for us...... Thanks