So I took out my newest pair of work boots, still quite dry and clean, and applied two coats of beeswax, rubbing it in well, and buffing to a slight shine on each coat.
All seemed to be going well, so I went out and spent the morning on longish wet grass.
Oh dear, somewhat less than successful. The right-hand boot (on the left in the picture) has a broad stripe of non-soaked leather across the top, but the rest of the toe area is quite damp.
It is clear from the photo below that the problem is worst where the boot bends.
Just in case I didn't apply the beeswax sufficiently diligently, I left them to dry, then applied another coat or two: however, same result, wet socks after just a couple of hours.
So the score so far is:
Dubbin: rubbish, does not work.
Beeswax: lovely soft leather, does not work.
Vaseline: doesn't work, but makes boots very supple and at least is very cheap.
Nikwax: utterly useless, both the "leather" one and the "nubuck" one.
If anyone has any further suggestions, I would love to hear from you...