The serial number is 212XX which dates this camera from a 1929 batch of 8,104 cameras, serial numbers 13,375 - 21,478 (from Leica Historica Band 1). Assuming that Leitz in 1929 would not have produced all 8,104 cameras in one go, they must have produced lots of smaller batches. Leica Historica Band 1 details production batches in great detail from 1930 onwards.
The camera is an export model (GB or USA) as the focusing scale is in feet and it is the close focus model (minimum focus distance 1.5 feet).
I e-mailed Leica to ask if they could check their factory delivery records, but they could not (or would not help) which is a pity as they would have the details of where this camera was delivered and its delivery date.
I realise that it is probably a request Leica get asked a lot and they probably do not have the resources available for this.
However Leica should realise that as well as collecting older Leitz equipment people like myself also buy lots of new equipment and are actually keeping them in business