Highly unlikely I know, since the thread was back in 2012 & the little girl involved will be grown up by now, but it was a real heart warmer & ended up in Classics.
I was reminded of it today when I saw this caterpillar in a charity shop, who must be related to the family somehow.
www.mumsnet.com/talk/mumsnet_classics/1309565-WWYD-The-Saga-of-the-Family-Tuna?page=1