Leonard Malcolm Saville was an English author best known for the Lone Pine series of children's books, many of which are set in Shropshire. His work emphasises location; the books include many vivid descriptions of English countryside, villages and sometimes towns.
This classic British adventure story for younger kids is rather Blyton-ish. Two siblings convalescing after an illness go to stay at the seaside. Adults are either absent (physically or mentally) or villainous. Food tastes better while on holiday (because of course it does!). The main appeal for me is the setting, since I have been to Cornwall - and specifically, Saint Michael's Mount - and enjoyed it very much. Alas, the Mount does not feature much in this story, which I feel was a missed opportunity.
This is a tame, everyday sort of adventure with no smugglers or camping or boat voyages in sight. The children are rather irritating too. I have nothing against a story of this type - indeed, I am very nostalgic about them - but this particular Saville book does not stand up well against Blyton's Secret or Adventure series, or even the Famous Five.