- a./ Stoke-on-Trent, England
- b./ Orange County, California
- c./ Nagano, Japan
- d./ Basle, Switzerland.
Answer below.
Being a construction of your humble blogger Tepid Halibut, with the aim of posting one vintage slide image per day, from now until Kingdom Come. (Or until Mr Halibut gets bored.)

A fine Indian Summer day here in slide-ville, spoiled only by a police helicopter announcing a missing 10-year old girl. <>
So, a final (?) summer shot from the archives - and I presume it's from family trip to an American Watery Theme Park. A chance for the (not very) extensive crowds to acknowledge the water-ski display team and ...umm...clown.
Bonus - Austrailians. Strange bunch. Disturbing sexy pie adverts. (Not a phrase I often type.)