Old BSA bicycle S399

[MattG]

Hello, I wonder if anyone out there might be able to assist ageing this bike?
On the underside of the pedal sprocket, it bears a punched 'S399'; possibly a serial number.
It is a ladies bike, with an old sprung Brookes saddle, complete with child seat.

Any ideas?
MattG

 

[focomat 1c]

The simplest way to date this bike is to look at the Sturmey Archer rear hub . You will find the date of manufacture stamped
on the body of the hub between the spoke flanges . The bike would have been built slightly after this date but will at least
give you some idea . The bike looks to be in remarkably good condition and with a thorough service and a good clean
followed by a wax polish could give years of pleasure .
My best guess for the date would be 1960