Sometimes you are lucky twice. We went to collect this beautiful Anker. And found there was a nice Singer 15 D Treadle machine available too. With exactly the style of cast iron base I was looking for.
To haul the Singer up the stairs it came apart in three manageable parts.
Here is the completed machine. Very pretty.
Serial number with C prefix tells us it was built in Germany between 1908 and 1940, but exact dating is more complicated as production records were lost. But this webpage at Toolfool suggests our machine was probably built in 1910.