We're going straight to the source. We're ringing the buzzer of Canal House. If someone answers the door, maybe they'll have the answer to our question.
No one answers.
And so we stand, squinting in front of this mildly ugly pebbledash house on Lisson Grove, north London, wondering why it's nicknamed the 'Upside-Down House'. Doesn't look very upside down to us.
It's more to look at, by the way, when you view it from the other side:
Canal House is the only abode to span the Regent's Canal, the occasional steaming narrowboat slipping beneath what we suppose is someone's living room. It's an odd building alright, a sort of austerity version of the old London Bridge. Although this doesn't excuse it from being not in any way upside down. Not if it's going to be nicknamed the Upside-Down House.
A previous, fleeting investigation into Canal House concluded "There's a plaque... but it doesn't really explain: 1) Why this house was built over the canal, or 2) Why it is upside down...".
We can't even find this nonsensical plaque to decide whether or not it's nonsensical. It's time to call the Canal & River Trust. They'll know.
"Surely the canal is more interesting than the house?," the apparently-baffled man on the other end says. He's almost certainly right. But we've become mildly obsessed about this trivial case of etymology, and won't let it lie. Not now.
Not an hour later we get our response. The house, we're informed, was built in 1902 for the person who controlled the coal barges, headed to and from Grove Road Electrical Substation. It's the only house to straddle the canal.
And it's called Upside Down House because... the entrance is on the upper storey. And that's it. No armchairs stuck to the ceiling. No Poppins-esque tea parties. Not an upside-down sausage.
We could argue that by this logic, it should be normal for houses to have canals running over their roofs. But we've expended enough time on this particular conundrum.
There are better upside-down houses in London — this facade on Blackfriars Road by Hackney artist Alex Chinneck...
... and this horizontal house in Hackney, where you can 'scale' the walls and 'hang' from window ledges...
... except — more disappointment — both of these are long gone.
But the bitter blow of Canal House's disappointment is mollified by the stretch of canal boats leading directly up to it. This linear towpath garden, lined with chocolate box boats and strewn with lanterns and discoballs, is what makes the trip still very much worth it.
Yup, turns out the canal is more interesting than the house.