Art pottery vase with Crane decoration

Lidded vase, 10cm tall, decorated with four Cranes in an identical pose. Perforated lid. Painted mark P.G. to base.

Not meant to be a negative, as the decoration looks very good, but because of the painted mark my guess is that it was a factory blank painted outside the factory by an amateur.

Yes, it seems like it. Also because you can see the paint over the foot ring.
Is the painting under the glaze?

I would say the decoration was under the glaze.

There are some noticeable differences between the quality of birds (perhaps more than I would have expected from someone used to churning these out) the one pictured is the best.

I'd be inclined to agree with SP to be honest, tho it may have been someone doing them professionally to sell at craft fairs/tourist shops etc.

Thanks to all for your suggestions.