In article , Fleetie wrote:
Why do some people mis-spell "shows" as "shews" and "shown" as "shewn"?

I've seen this many more times than I would expect, since it seems a very
unlikely mis-spelling to me.

I even saw it on a QUAD valve amplifier circuit diagram from the official
manual. (Decades old, of course.)

Is there something more than mere illiteracy at work here?

Yes, archaism.

The OED lists "shew" as a variation of "show", so I guess that's how it used
to be spelt.

Rod.