Brokenwood is a historic producer to me, because, long before Australia was famous for this grape, winemaker Iain Riggs made sure the facilities were set up for white wine production and with his early vintages he helped put Hunter Valley semillon on the map (along with Tyrrell's, who has been making semillon since the early 1970s).
White wines like these, with such massive aging capabilities, are hard to come by; but I am stocking up on some sleepers for a future era!