Great Britain cacellation date

[mac123]

Sorry for the obvious nature of the question, but I am looking for greater certainty about the YEAR of this postmark.

I believe the correct date is June 21, 1911.

But I don't have the postmark catalog nor do I specialize in the subject.

Thank you very much.

[guyana1230]

Yep, correct. Date is June 21 1911 and evening post (6:45pm or 18:45). No idea what the 21 is for though.

[mac123]

Thank you.

[I.M. DeBear]

mac123, guyana1230, That doesn't appear to be an ordinary round cancel. More like a scalloped diamond with rounded points. I don't know much about GB cancels, but in Europe certain shapes often indicated specific usages. The use of oval cancels on Railway Post Offices is a good example. The explanation for the 21 at bottom is likely tied up somewhere in this (a route, office, ship, etc.) This seems like a great opportunity for some SB with the right book to enlighten us all. Any takers?