"Of course the commissioner has to live in an appropriate residence, but there was nothing wrong with the old residence," he said.
The ministry confirmed yesterday they had entered into a conditional agreement to sell the property.
Jordan Williams of the Taxpayers' Union, a watchdog on political spending, questioned why it was taking so long to sell the residence.
"The last time I looked the London property market is booming."
Sir Lockwood, 65, has settled quickly into the London diplomatic scene. On Friday he was guest speaker at a function for The Worshipful Company of Vintners, a trade group.
He used the occasion to argue that too many "great New Zealand wines" are unavailable in London, trade publication Drinks Business reported.
Sir Lockwood said he struggled to find top New Zealand chardonnays in his favourite restaurants and shops there.
"Our best chardonnays are stunning and they are not available in London," he said, adding that he had to bring them across himself.
New Zealand Winegrowers said it was an honour that a Kiwi was invited to speak at such an "august" institution as the Vintners group.
"There are also a lot of small producers of chardonnay who don't export, who make fantastic wines, and that's probably what Sir Lockwood is talking about, having to tuck a few bottles into his bag to take over with him,'' global marketing director Chris Yorke.
New Zealand exports 4.9 million litres of chardonnay a year, compared to 150 million litres of sauvignon blanc, and 9.8 million litres of pinot noir.
The UK, which was for years the biggest market for New Zealand wine exporters, has now slipped behind Australia and the US.
"New Zealand wine tells such a good story about us,'' said Mr Yorke. "It's a high quality product, it comes from many regions, it's sustainable, and at consumption, it is identifiably from New Zealand.''