Purchased this watch from the States about 6 weeks ago - 10k RGP - musical note like lugs. I had the back off and there was a retainer to hold the movement tight in the case. This was spring like and it was a devil of a job to get back - I forgot to make a note of the movement number. I don 't feel inclined to have another look!
I'm good with a tentative ID of "21st Century".
We have no ad for Ivanhoe, and I think the original ID was based on a crystal specs ID suggesting an Ivanhoe model exists. I can't find the thread w/ the Ivanhoe crystal discussion, but if I remember correctly, that Ivanhoe crystal didn't fit this watch.
For 21st Century, we have the Spanish Siglo 21 ad. While there is a period-correct crystal package w/ model name "21st Century" which does not fit this watch, it does not rule out the model name being used for this ID. Bobbee found at least three different "21st Century" watches in the price lists....and for me, vintage ads trump crystal specs- even when translated from another language.
One could argue for unknown ID based on all this, but I won't start that discussion. I'll participate if someone else wants to go down that road.