Great Britain Cover With Some Sort Of Frank

Hello all. What I have here is a cover from Great Britain bearing some sort of frank. It doesn't look like a postage meter because there is no meter number evident (and I didn't find it in the on-line International Postage Meter Stamp Catalog). I don't think it is a cancellation either because it is inscribed "Paid". So, what is it?




Here is a close-up:



Any responses will be greatly appreciated.
Regards, Robert

(and I didn't find it in the on-line International Postage Meter Stamp Catalog). I don't think it is a cancellation either because it is inscribed "Paid". So, what is it?



Even though it is not in the reference you mentioned, I am still inclined to think that it is a type of meter cancellation that is yet to be recorded????

Maybe someone more knowledgeable in this field can provide an answer?

Chimo

Bujutsu

Another interesting point is that the rate for the USA in 1948 was 5d.
Are there any other markings on the cover ??

This is listed in the "Collect British Postmarks" handbook under machine cancels. The machine maker is Sylbe and first used in 1907-8.

The cover has no other markings--the back is clean.

So, it's a machine cancel, yet no stamps were applied to the cover for it to cancel. It has a franking power of 1/2d, yet the rate to the USA in 1948 was 5d. Interesting.

Thank you all for your responses.
Cheers, Robert

I believe the Royal College of Nursing (a governing body for UK nurses) had or maybe still has their HQ in Croydon, Surrey... hence the metered mail impression on the cover. They probably sent hundreds if not thousands of letters to their members so used this method to save time and effort. I cannot explain the recipients address though!!

The slogan isn't unique to Croydon as there were 350 dies in place in 1948 for this slogan.