Antonia Forest fans

That seems instinctively more plausible, but it's not actually specified in the text, and Nicola seems quite sanguine about being pudding-basined at the ripe old age of thirteen. Even if we take the revival of the pudding-basin theme at the end of the chapter as entirely in jest (and I'm really not sure whether it is or not), I don't get the sense -- at least textually; I am obviously not trying to make any wider historical point here! -- that pudding-basin hair-cuts are exclusively linked to early childhood, in the way that, say, a comfort blanket or a dummy or a potty would be. One certainly could read it as a reference to their Pam and Molly's young childhood, but looking at the text in detail it does seem to me that it's presented as a semi-funny but also semi-realistic alternative. In which case, wow, weird! -- and all the Mme Orly speculation follows.