Scottish Iain MacCormack Zoomorphic Banded Agate Celtic Brooch

Made in Scotland by Iain MacCormack of Iona island. This brooch is set with an oval red / brown banded agate cabochon. There are 4 creatures that look like eagles or serpents heads entwined in complex Celtic knotting. This brooch shows little to no wear. The roll-over clasp is in good working order. Fully signed on the back. Measures approximately 2 1/2" x 1". Estimate this brooch from the 1950's.