Hi Seddon,
OK, you have an F300 Seamaster Chronometer.
F300 refers to the movement, which has a "tuning fork" movement. Why 300 ? Because the tuning forks vibrate at 300 hz. If you hold it to your ear, when its running, you should hear it "hum".
Work colleagues , friends & family will look at you like an idiot, when you do it for the 25th time on the same day, but that's never stopped me yet :-)
These movements were basically the predecessor to the quartz movement.
IMHO the best website to read for Info on F300's is Rob B's Accutron site . The Accutron / Bulova/ Omega movements were all very closely related.
At the time this was probably the best & most accurate movement available.
I'm not sure of the exact age of your watch, but the movement was available from 1972 onwards ( 98,000 were made )
As far as I know almost all f300's were chronometer rated.
As to the actual watch. It's not a watch that I have any practical experience of. I may add one to my collection one day though.
That particular model seems to have been quite popular. I have 3 adverts on my website featuring it ( OK these versions don't havethe day, just a date feature, but it's basically the same watch )
f300 adverts, scroll down to Concorde & look after that .
Here's one of the pages
If you check out the prices ( in the concorde advert ), you'll see it cost more than the PloProf & the Speedmaster of the same period. Unfortunately current prices don't reflect this.
Your watch looks to be original. It has the correct hands, dial & bracelet.
All in All a fine example of one of Omegas best watches of the time.
Enjoy it.
Steve