I assume that more branches mean a stronger wind but how many knots per branch?

What are the readings based on? The location of the feathers don't seem to correspond to the met office spot find chart (form 214) or the TAF/METAR forecast locations.

Is the direction away from the start of tip of the feather?

Thanks!

SkyDemon is an international product and as such uses an international wind forecast model designed for aviation. The numbers shown at points will of course not always correspond "exactly" with a local chart produced by any national body, as all forecasts show different results. It should always be very close, though.

I am surprised that the interpretation of wind barbs was an issue here; are they no longer teaching this as part of the PPL?