Hi Paul, I keep coming back to this one and am still unable to find any info on 23 jewel Ambassadors. I suspect this is a model produced for and sold to the European market. If that is the case, we will probably never find a specific variant due to lack of reference material available for non-US produced watches. I did a search for "Ambassador 23 jewel" in the database and there are only 3 examples - all are dial marked like subject watch, and dated 1972. All have a s/n starting with "3 - " and case marked "MRP" which is the case maker signature, as well as "Swiss".
No doubt it's a
1973 Ambassador
and it has signs of being an international model, as opposed to a US production. The fact it was purchased second hand in Manchester is also a clue.