Well more then 1000 cards of our late grand father Norman John Birkett (G3EKX- plain NEW /not usedcards about  1  1/2” thick)& RAF ARS plain cards & misc. related radio cards very old letters (with nice stamps) etc.
These have all come from one estate / one ham radio operator's collection. Dad was manufacturing the communication equipment in his younger days- SSB- Delta, Sphinx, Canonball, SWR bridges..
I am not an expert in QSL cards but I can tell you about my observations.
Also, please understand that I could not possibly take the time to look at every card to compile exact statistics on the lot.  My numbers are approximate and I promise you that I've put in my best effort to not be inaccurate (with 4- our- children running about..).
1990-1994 five cards
1980-1990- about 60 cards incl. cardboard one from St. Austell brewery, Cornish pirate flag, Imperial war museum Duxford (Spitfire), Goonhilly Down Earth station, few from Poland, Germany etc.
1960-1970- about 230 cards incl. South Africa-Kenya, Czechoslovakia, , Germany, USA- Pensylvania, Switzerland, Romania, Austria, Argentina, Denmark, USSR- Odessa, Moscow, Leningrad,...Argentina, Denmark, Norway, Isle of Man, Hungary, India, Canterbury etc. 
1950-1960- about 500 cards incl. Bahrain, Ireland, Germany, USSR- Leningrad, Krasnowodsk, Nairobi, Israel, New Zealand, Japan, Australia-Melbourne, Austria, Gauchos Land-Urugway, Sweden, Pretoria-South Africa, Luxembourg, Ecuador, Jamaica, Sicilia, Hungary, , Nederand, USA- Ohio, Texas, NY, Romania, Bahrain, Turkey, Argentina, Canterbury cathedral etc
1940-1950- about 170 cards incl. Czechoslovakia, Germany-Bavaria, Karlsruhe.., Netherlands, Belgium, Sweden, Bath spa etc
plus two bigger postcards QSL (17.5x12.5 cm approx from 1950’s)
  • The largest percentage of cards seems to be from the 1950's
  • Approximately 75% were sent as post cards and have wonderful old stamps attached to them on the backs.
  • There are plenty from the 60's, 70's, and 80's.
  • The owner of this lot was originally from Cornwall (previously in Derby).  It seems like maybe at least 50% are from the New England/New York/Northeast region but there are definitely a lot from all over the country as well as many international.
  • Regarding potential duplication, I think these were originally sorted by hertz/frequency, but please understand again that I could not go through them all one by one.  While flipping through and setting up for the above photos, I probably noticed about 3 or 4 duplicates total.  It may have even been the case that one card was sent to him in the 50's and then another in the 60's or 70's because they may have had different writing on them.  If this holds true throughout, then the amount of duplication would be EXTREMELY low.

Overall the condition seems to be very good.  Some better and some worse, but overall I think anyone would be very satisfied with 99% of them.  It seems like these were stored properly for all these decades.  Some may have age appropriate tanning, but there is none of that "basement smell."  I would consider the lot extremely satisfying.

What a beautiful assortment of cards.  Many picture and artistic cards.  Some very nostalgic.  I'll also include a small packet that has some of this original owner's cards for his set-up.
I know this is a large lot but I unfortunately do not have the time to split these up into smaller lots.  Please feel free to use the "Best Offer" option above. Have few more pictures I can send you if interested.
Also, as kindly as I can possibly ask, please no requests to break up the lot or search for individual cards.  This is already packaged and ready to be shipped.
Box is full 26.5 x 37x 14.5 cm
weighs just under 4 kg
Thank you to everyone for your time in looking at the listing.  Please feel free to send any questions or comments my way.

Thank you again.