none of them have a dummy now but one of DD2's friends in Yr4 still sucks her fingers like she did as a baby!!

SO true. My mum always said to give the suckers a dummy because "you can throw away a dummy but you can't throw away a thumb"
My playfriend when I was little was still sucking her thumb all the time at 8 which of course led to teeth issues.
As soon as Ash stuck his fingers in to settle I stuck a dummy in