Dating Arabia Finland Pottery from Unknown Mark

I recently purchased a beautiful Arabia Finland sugar bowl and creamer set. Love the design and color!
Based on my research, the designer is Ulla Procope and this is her Anemone pattern.

BUT, when it came to trying to date this set, I had to finally give up. None of the sites showing Arabia marks listed this one. To me it resembles a covered casserole dish inside a half circle. I did find a few pieces for sale (eBay, etc.) that had this mark and some of them were marked "Made in England" while others had "Made in Finland" like mine. The ones that were dated ranged from 1950s-1970s, which may be just a guess based on the designer (Ulla Procope). Is there anyone who can help solve this mystery?