Curiosity - unusual, but interesting

I would love to know the provenance behind this structure! It stands in High Street, Willoughby, and last traded in August 2001 for $660,000. At the moment, it is valued at about $2,000,000 give or take $200,000. As you might suspect, the front is deceptive as Google Maps reveals it to be an extensive property, with banks of solar-panels to heat an outdoor pool. It sits on 672 square metres of land. Willoughby is an old suburb, and weather-board houses, although not rare, are not a dime a dozen, either. But, what is with the shingles, and the key-hole cutout?