The theme of this week’s show is water and, while four of the shortlisted houses are on the coast or riverbank, 6 Wood Lane is on the landlocked slopes of Highgate.
The roof resembles an upturned hull, there are portholes for windows, a gangplank leads to the front door and there’s even a lighthouse at the very top.
Twelve years in the making, it was the obsession of Mike Russum, who lives there with his wife Sally Cox.
The top 20: RIBA House of the Year longlist
The judges described the house as a ship run aground in suburbia, while presenter Kevin McCloud likens the interiors of the north London home to a Jules Verne-style spaceship that feels ready to take off from the narrow spot between its multi-million pound Georgian and Victorian neighbours.
“Who wouldn’t want to sail away in this building for the rest of their lives?” he wonders.
“Very few buildings are there to help the imagination to flourish and fewer are wellsprings of inspiration, but this place is.”
An extraordinary, but perhaps more expected water-related design is the rippling clifftop Ness Point in Dover, Kent, which opens tonight’s programme.
Interior designer Logan McWatt demolished his parents’ conventionally designed home to build the Thirties modernism-inspired curved white mansion on the cliffs, described by judge Michelle Ogundehin as a “modern-day castle, clever, flexible and future proof”.
The house not only impressed the judges with its curves that beautifully echo those of the cliff, but also with its ingenious interior.
A series of partitions and folding walls enable the rooms on each floor to be made to disappear and form one vast space.
Also featured is South Street in the historic town of Lewes, East Sussex. The house attracted the ire of planners and local people because it is clad in deliberately rusted mesh steel.
Stephen and Anita Yeomans turned the site of a former cement works on the bank of the river Ouse into something that McCloud says: “It may appear fierce and brutal outside, but it is warm and lovely inside.”
However, judges described it as “window to the world” and despite the controversy, architect Sandy Rendel says: “I like to think it might open people’s minds to modern architecture.”
The house most in touch with the aquatic theme of the programme is Redshank in the Colne Point nature reserve in Essex.
For, twice a day, it is surrounded by water as the tide floods the salt marshes it sits on.
Designed as a one-bedroom house cum studio for owner Marcus Taylor, he and his architect Lisa Shell literally fought the elements to create this cork-clad jewel of a house that covers just 40sq metres.
“Builders’ tools often floated off down the creek at high tide,” says Taylor.
Emphasising sea views rather than a twice-daily drenching, Archie and Trisha McDonald created Edinburgh Road that now offers a “Cinemascope” views of the sea off the Scottish coast in East Lothian.
Working closely with their architect Matthew Johnson, the McDonalds replaced the crumbling converted stable block with a flat-roofed bungalow with a larch-clad extension featuring a vast open-plan living room — complete with those views.
McCloud says: “The sense of connection with the sea couldn’t be closer.”
RIBA House of the Year, Channel 4, Tuesdays 9pm