Help ID this GB Cancel

[airbornestamps]

I can not find any reference to this cancel... 19 bar oval with "S" and "16" on a Sc #33

[malolo]

Hi - check this 1909 reference

reference pdf link 

footnote on page 47 explains why it could be difficult to find a London Southern District cancel listing.

[airbornestamps]

What a reference book that is!! I am amazed at how well learned this forum is, and the in depth level of information it provides!!  Thank you!!