Just as the year draws to a close news reaches us of a bumper country estate sale in Northern Ireland. It's not often an estate goes on the market for £5 million and ends up selling for almost double that, but Dundarave Estate in the pretty village of Bushmills, Co Antrim has just sold for close to £10 million (€12.6 million).

When we visited the historic 19th century home in June, it was selling on 550 acres, but when news came through this week that subsidiaries of Randox, a Crumlin-based medical analysis company had bought it for an "undisclosed sum", we noted the land size had increased to 1,200 acres.

It turns out that the sale – which was handled by Savills here and in the UK – includes 600 acres of estate land some of which had been set aside as an option for a developer who secured planning permission on it for a hotel and 18-hole golf course.

The purchase option expired a couple of months ago, and the lands reverted back to the clan Macnaghten who have used the estate as a summer residence since the 1920s. It is the biggest country estate transaction on the island this year and a nice return for beneficiaries Sir Malcolm Macnaghten and his relatives. When we met Sir Malcolm last he was flying Easyjet back to his modest life in the UK as a project manager and wondering what to do with all those enormous marble busts in the Great Hall.