(SOLVED)Boy stops Greek (?) island development when he finds a hidden temple [s]

[Fran]

I read this in the mid-eighties but i think it was fairly old even then and i am very hazy on details. I had a hardback copy, it had a white cover and possibly blue writing and i *think* there was an owl featured on the cover.
The story follows a young boy and his female friend who live on a Greek (i think) island, he has a pet cat and together they have adventures. This particular book involves some kind of building or development on the island that the children stop when they find a hidden temple - possibly dedicated to Athena as i remember an owl or owls featuring, it was a bit supernatural and it's definitely NOT "My Family and other Animals" by Gerald Durrell ;o)
I think it was written by a woman and for some reason i have "wing" "wings" and "feathers" floating round my brain.

I would love to track this book down, thanks in advance for any help,
Fran x

[Fran]

Someone on the Girlsown list has come up trumps and it's either "five from me, five from you" or "circle of stones" by Shelagh MacDonald
A Circle of Stones
Five from Me, Five from You