Do all the women in Ambridge have fingers that are all the same size?

Rob has had an engagement ring made for Helen, and got the size right by borrowing a ring, at random, from her dressing table. When Caroline got engaged a few years back it was the same story.
I am neither married nor engaged, so if someone took one of my rings, the only finger it would be guaranteed NOT to fit would be the ring finger on my left hand.

PS The first prediction above was wrong - but I'm still holding out for the second.