These pgs bring back memories. I only ever had the first one (a pig in a nappy) which I got when my parents opened my account. I think you were supposed to get the next one up if you saved so much and then the next one was a higher savings, etc.
I only got 50p a week pocket money and I'd rather have spent my hard earned (I swept leaves from the path) on Jelly Tots and Kinder Eggs. Sad thing is, even though I never got the £25 needed to get the next pig up, I still had more savings when I was 9 than I do now :(