Children's Mystery: Clues, Treasure in the Walls?

Sorry just to ask about children's stories, folks, but they're the ones that I seem to have the most trouble finding. I read one when I was young that was a children's mystery about four children--siblings, probably--who moved to an old house and found a secret code that led to some treasure in the walls. Similar to a cross between The Westing Game and the Boxcar Children, maybe? If I had to guess, it was probably published from the '60s-'80s--apologies about how wide the date range is, but I really have no idea myself. Anyone know this one?

SOLVED by Tina_Evans: Key to the Treasure, by Peggy Parish.

Could it possibly be The Four Story Mistake by Elizabeth Enright?

One of the Enid Blyton "Famous 5" books? There are four children (siblings and a cousin) and one dog = therefore 5.

https://en.wikipedia.org/wiki/The_Famous_Five_(series)

There's lots of them, and they all tend to involve mysteries or codes or maps or secrets, and of course, treasures.

These are excellent answers. Thanks to you both.

While it may be an Enid Blyton "Famous Five" book, for some reason I don't think so. Based on the Wikipedia page, too, I can't find one in which they're at a new house and find treasure in the walls--which is almost definite in my memory.

Let me add that I think there was a pen-and-ink drawing on the cover (that may be completely unhelpful, of course, because there were probably several different covers) and that there's a scene in which the heroes are dejected because they can't find the treasure (there's an old parchment or something that gives them clues--no, not The Goonies! :) ), but then the youngest (I think) discovers that the last clue actually means something else. Then I distinctly remember that the wall opens, revealing the treasure.

The Four Story Mistake is very, very close, so close that it may be the one. I don't know why I don't think it is, but, in looking everything over, I don't think so.

Many thanks again, though!

www.oldchildrensbooks.com might be a good resource

www.childrensmysterybooks.org is another

Peggy Parish has a series with three siblings, maybe not what you're looking for but maybe good reading anyway.

Any of https://www.librarything.com/tag/children%27s,+treasure?

It's been decades since I read them, so I'm not sure anymore how close these might be, but maybe:

The house of secrets by Nina Bawden
or
Secret of the old post-box (aka Mystery of the Empty House) by Dorothy Sterling

Many thanks, everyone! Apologies for not responding sooner, but I haven't had an opportunity for the last few days.

Tina, thanks for the links. The first of Peggy Parish's series, Key to the Treasure is very close. It may be it, but I'm just not sure. Anyone happen to have an extract or something? I found a brief extract on Google, but nothing big enough for concrete memories.

Thanks for that list, Konallis. It's probably on there, but I don't know which one!

Excellent choices, Foretopman. I know for a fact--I should have written this before--that "my" book takes place in the U.S., not England, so it's probably not The House of Secrets. It's similar to Secret of the Old Postbox, but the plot description doesn't ring any kind of a bell--except for one element, the "American Revolution and other historical events" bit. I don't know if that helps any.

Thanks again to all of you.

Each summer Lisa, Bill, and Jed visit their grandparents, and they hear the story of the sketches hung above the mantel. The sketches are clues to a hidden treasure, and no one has been able to figure them out for a century. There is a missing first clue, but when the children stumble upon the second clue, they're on their way. Could it be that on this visit they will solve the secret that has eluded so many for more than a hundred years?

Thanks, Tina. It seems rather close. I'll hunt down a copy and let you all know.

>4 Nalkarj: I hope you do find it; it's always nice to have this sort of loose end tied up. Even if Four Story Mistake isn't what you are seeking, it is worth reading :)

Thanks, Darth-Heather. I do so very much appreciate it.

It was nice to have the other loose end--about the story "Drawing the Moon"--tied up. I didn't think that would ever be solved!

I will check out Four Story Mistake--thanks for the recommendation!

No idea what it is so a suggestion. Sea View Secret, by Elizabeth Kinsey.

I haven't written it here, but I've found several reviews of Peggy Parish's Key to the Treasure, and I think it's the one. Thank you all for your suggestions and recommendations!