Mercian
I live for the CABE
The serial numbers are:
Boy's: L248436 and is a 3 Star Deluxe= 1947 I believe.
Girl's: M492082 and is a Special Deluxe = 1949 I believe.
Hi Deb,
I agree, L = 1947, M345446+ = 1949.
1947.……L5001 - L313474
1948.……M - 5001 - M345445
1949.……M345446 - M525640
Here is a table by Mr. Columbia on Wayback for dating Columbia's in case it's useful to you in future.
https://web.archive.org/web/20180318104158/http://www.vintagecolumbiabikes.com/id79.html
I hope this helps,
Best Regards,
Adrian