It also depends what we call "empty house". Your link doesn't provide a definition. Is a house occupied a few weeks a year considered empty?

True, but citing data from 2017 is also a little misleading, considering theirs was a very recent anecdote. It's still probably relevant though.

Contra:

> The Square Mile has the highest percentage of empty homes in the entire country, fresh data states.

> Some 42.4 properties per 1,000 sit unused in the City of London, leaving it top of the charts and the only London authority to feature in the nationwide top 10.

> Data compiled by insurer Admiral also shows that as many as 29,242 London homes have been unoccupied for at least six months, to a collective value of roughly £15 billion.

* https://www.citymatters.london/vacant-homes-city-london/

4.2% is a lot less than 70%.

That's because real vacancy (as in, untenanted) only makes up a small percentage of the empty houses. The rest are owned by wealthy foreigners who reside there a few weeks in the summer and leave it to the care of a caretaker (who does not live there of course) for the rest of the year. Some of the obscenely wealthy may even have a live in concierge who lives in his own rooms keeping the rest of the house ready for its owners all year round.