I remembered loving this as a kid, so - as I do from time to time - I gave it another read to see if it stood the test of ages. It absolutely did. I was charmed all over again. 

Major caveat - there were a couple of very serious jumpscares from some of the language (yes, homophobic slur that must somehow have been in relatively casual parlance in 1979 ?! - totally unrelated to plot - it could and should be changed with minimal effect on the writing).