Primary school early 80s. We used to get Puffin Books leaflets to take home. I seem to remember they were massive but they were probably quite small.
I spent hours poring over it as I was allowed to choose one book. Then it would feel like months went by until the 'office lady' would arrive with a huge pile books and they'd sit on the teachers desk until she handed them out at home time. It was so exciting.
I remember getting 'The Worst Witch' and 'Stories for 9 year olds' which (I think) had The Necklace of Raindrops in it.
My children's school did similar with 'The Book People' but I don't think they ever reached the same level if excitement as I did with Puffin Books 