German/Belgian Salt Glazed Jug Winged Goddess Design. ID Help

10 inches tall, cobalt salt glaze stoneware. Decorated with (not by) winged goddess looking women. It's stamped 664 and looks like an incised 7 or L
I'm really having trouble finding anything with this design on the web. I bought it on a car boot browse and it caught my eye. I asked but there was no info to be gained from the seller.
Could anyone tell me if it's likely to be German and a rough age....in fact anything please.

its Westerwald Saltglazed stoneware but they copied the same designs for centuries to without a makers mark it's hard to tell.
I would say mid 20th Century

Thank you, maybe a fortunate find. It's very striking, the cobalt is gorgeous...in fact I also bought a Hubert Krumeich-Remy Cobalt vase for myself at the same boot sale, quite unlike my usual fancies but I think sometimes you see a beauty and that's all it takes....
This one is not really going to stay with me long, many thanks for identifying it for me..I was getting nowhere.