Did JK Rowling Read This Book?

I have spoken before of my love for Monica Dickens, so I couldn't resist this first edition (1948), though I was pleased and surprised to discover today that Joy and Josephine is still in print. It's a lively, delightful version of the swapped-at-birth story; adopted at birth by the Abingers, grocers on the Portobello Rd, Joy/Jo might be the foundling daughter of a poor Irish girl, or she might be the niece of wealthy, titled, Sir Rodney Cope. She gets to taste the possibilities of both identities, and decides (or at least I think she'll decide -- I haven't quite finished it yet) to live out her life as herself.

But that's not what caught my eye! I offer for your consideration page 151:

"You'd have been captain of Second Netball this year, wouldn't you? I wonder who they -- gosh! Tonks will be it, I suppose." ... (S)he sped away to break the glad news to Tonks Tonkinson...

And then p 153:

There was nothing unusual about a girl of nearly fifteen starting regular work... Joan Lupin (was) already earning good money at the button factory...

Tonks AND Lupin?? In the space of two pages? Coincidence? Or -- is it witchcraft?