A remark on the cover says a children's book.  I'd say YA - but actually, if you find this and take the time to read it, you can be any age over (say) 10 years.  Starting at the very  beginning of the 20th Century and leading up to and through WW1, this is a wonderful and gripping read. And for the chosen audience, an insight into a time long gone (and a super glossary at the end to explain things no longer commonly used or spoken of;  certainly worth referring to for any reader).  The Skylarks are three cousins who spend summer holidays in Cornwall with grandparents, and throughout their childhoods, they look forward to this more than anything in the world.  But we all grow up, and for them, war advances and things change.  The first third of the book is funny, sunny and bright, and the second two thirds are not, dealing as they do with the war, and the losses of that dreadful time.