It is easy to see why. What first strikes you about the place is its dimensions and spaciousness - qualities not shared by the ranks of tall but slim Victorian terraced houses found in the leafy streets around it. "Its vast open-plan layout is unique," says Monty. "It's unheard of to find a lateral space of this size in this area."
Clutter has also been kept to a minimum, with nothing being allowed to interrupt the symmetry and flow of space. Even the doors are disguised as panelling; they lack handles but can be slid back along invisible grooves. This makes it the perfect play space for Yasmin. "She loves it," says Monty, "and is constantly whizzing around the second-floor living area on her little bike."
The spaciousness of the apartment is enhanced too by the extensive use of glass - apart from floor-to-ceiling windows and skylights, it also features in the partitioning and chunky but transparent balustrades skirting the upper level's gallery area.
The sense of lightness and airiness is also helped by the series of decked terraces ringing the apartment, from which fabulous views across Regent's Park and beyond towards the Telecom Tower can be enjoyed. It was an ideal spot to develop - a largely derelict site directly adjoining Regent's Canal, close to local shops and just a few minutes' walk from two of the capital's most beautiful parks.
The idea was for a development incorporating a restaurant and delicatessen at ground level with the three upper floors devoted to offices and flats. However, obtaining planning permission was no easy matter and encountered stiff opposition.
"Primrose Hill is a conservation area and this project was the first significant new build that had been proposed for about 100 years," says Monty. "It took us a good 18 months of lengthy consultations with the local authority and conservation groups before we got the go-ahead."
Even when the permission was forthcoming, there were provisos. A protection order was slapped on a section of subterranean horse tunnel found on the site - part of an elaborate Victorian network that was employed to move horses from their stables in Camden to various other sites around the capital. The tunnel was eventually incorporated into the restaurant's design. An old water tower also had to be preserved and this now serves as the building's lift-shaft.
However, in spite of the early concerns, the development has proved a success. The Sardinian restaurant and up-market English delicatessen are both doing good business, while the building itself has become a local landmark. There is something eye-catching and distinctly nautical about the design - both in its overall U-shape as well as in details such as the cylindrical ceiling on the penthouse's second floor. This is something of a signature theme of the architect Paskin Kyriakides Sands - also responsible for the design of the Putney Bridge Restaurant, on south London's Lower Richmond Road, which is shaped like the prow of an ocean liner.
Such attention to detail is also a mark of the penthouse's internal design. All four bedrooms, three of them en suite, are located on the lower level, while the top floor is devoted to the open-plan living/dining area with a sumptuously appointed kitchen fitted with top-of-the-range Poggenpohl units and Gaggenau appliances. The flooring is walnut in the living areas and limestone in the bathrooms.
Nor is the sophisticated gadgetry restricted to the kitchen. "We have all the latest toys," says Monty. There is round-the-clock video surveillance of all common areas, including internal parking spaces, while other hi-tech features inside the apartment include underfloor heating, air conditioning, Lutron lighting and electronically operated blinds and curtains.
All of the internal features and fittings - such as the magnificent central staircase - are one-off, tailor-made creations. The tables, chairs and beds - all made of solid walnut and included in the asking price - were likewise individually commissioned. Prior to becoming a property developer, Montyworked as a furniture designer and this made him a hard taskmaster for the various contractors involved in the project. "I'm sure I drove everybody nuts with my attention to detail," he says.
So fanatical did he become that he even commissioned a pair of bespoke stainless steel baby gates to stop Yasmin falling down the stairs. "I just couldn't face installing some of those naff white plastic ones you find in the shops," he says. "They cost me a bomb though - £2,500 for the pair of them - and I think that that probably makes them the most expensive baby gates in the world.'
It is obviously going to be a terrible wrench leaving all this behind when the family eventually quit Primrose Hill to move into the new family home Monty is working on in the countryside just outside Windsor. "This penthouse was never built to be sold," he says, "and with so much time and care invested in it, we're going to miss it enormously."
Get the spec
What's for sale: Luxury penthouse apartment occupying two floors, comprising study, store room and three bedrooms with en suite bathrooms on lower level, and a vast open-plan living room, dining room and kitchen above.
How big? 5,000 sq ft.
Serious kit: Walnut and limestone flooring throughout, bespoke furniture and fittings, kitchen units by Poggenpohl and appliances by Gaggenau, panoramic views across London.
Extras: All mod cons, including integral double garage, 24-hour security, air conditioning, under-floor heating, audio-visual in all rooms, Lutron lighting and electronically regulated blinds and curtains.
Buy it: Goldschmidt & Howland, 020 7289 6666, for £3m.
The Span Group can be contacted on 020 7428 5822 or at firstname.lastname@example.org.Reuse content