The first two covers in this post were a feature of my childhood. The books lay around the house for many years. I read them both but don't remember much about them except a dark, atmospheric brooding feeling that seemed associated with them, perhaps because of the artwork. Maybe at the time I was given them I was a little too young but for some reason they didn't 'catch' at that point.
For the last month I have been voraciously reading my way through the series. I can't recommend them highly enough to anyone, young or old. The Dark is Rising in particular, (the whole sequence is called that but I mean the second book) is a masterpiece and if you have seen the dismal American film version don't be put off! The whole series is a children's fantasy sequence based on British and Celtic mythologies in a unique and imaginative way with some breathtaking courage in the storytelling throughout. Over Sea, Under Stone is perhaps intended for slightly younger readers but remains compelling and then the whole thing takes off with the rest of the series.
So, having had the first two books around for years and being accustomed to this montage-style of artwork on the covers by Michael Heslop, obviously the collector in me wanted to find the rest of these Puffin paperbacks with his covers on them. But I couldn't find anyone selling the last book in a Michael Heslop cover and, in the end, I was so desperate to read it that I gave in and ordered a copy that had the more modern reprint cover, which arrived this morning... and low and behold, it was the one I wanted in pristine condition... So, sometimes that Amazon lottery can work in your favour as well as against.