I had a copy of that when I was a child. I used to be given a Rupert annual every year by my maternal grandmother's twin sister.
I was sorely tempted to buy it. My mother gave away most of our childhood books when I and my brother got too old for them. As a result, although I have memories of the books, I don't have the books themselves. My mother's own mother did a similar thing, giving away the books we used to read when we stayed with her during the summer holidays.
Losing the books was rather saddening for me. Obviously, I wasn't going to read them ever again anyway, but they represented a connection to happy times. Giving away the books was like saying that the happy times would never return. They won't, of course — you're only young once — but for a few moments those times can be recaptured. Seeing an old favourite and reminiscing re-establishes a connection, which even if it's only transient is nevertheless a lovely feeling to have.
I have maybe 30 or more Just William books in the attic that I saved before my mother gave them away. I haven't read most of them more than once, but they serve to show that my fond, wistful childhood memories are real. If I could have saved even half a dozen of my other favourite books, I'd have been satisfied.
Oh well. I just hope that the children who were given them derived as much joy from them as I did.
Today's children may well have to make do with texts read on electronic readers, but I'm sure they'll cope.