It could just as likely be May 25, 1902 since the lock body design has been around since the 1890's. You could probably better determine the date by when the Southern Railway started business under that name.
BBE.
Printable View
Wikipedia states that Southern Railway started using that name in 1894, until 1990. The style of lock body includes many years, but how about the stepped shackle; could that be used to narrow down the general time, e.g. if Yale introduced it in 1910 then the 1902 date could be discounted.
And, I know that Miller "pancake" locks can be roughly dated via details like pin placements and scroll marks. Are there details like these that can help with Yale padlocks?
Yale never used ECO's or ECN's but instead called their version an Authorization. Those were filed in engineering and listed on drawings. If you found your way to engineering and could convince someone to look up the part number, you would have the date.
Most of the engineers were old when I was there and now I am old and they are retired.
:-). Good luck.
BBE.