In the early 1990s Queen Silvia of Sweden watched Alzheimer’s disease pull apart the threads of her mother’s mind.

A quarter of a century later the experience has informed the design of a set of dementia-friendly prefabricated apartments that could soon be erected in Britain.

The queen, together with the founder of the Ikea furniture chain, drew up the plans for the first prototypes of low-cost modular flats to ensure that patients and their carers could continue to live in their own homes.

The six model apartments in Stockholm are a pilot for a concept that is intended to be spread across Scandinavia and into the UK over the next few years.

Patients and their carers could continue to live in their own homes.

“In Sweden the number of people aged 80 or over will increase by 85 per cent from 2015 to 2030,” Jonas Spangenberg, chief executive of BoKlok, the building company that made them, said.

“Society needs to find a solution where more people can stay at home for longer; and actually people want to stay in their own home. This is also much cheaper for everybody.”

The idea emerged several years ago when Ingvar Kamprad, the Ikea billionaire, made a large donation to Queen Silvia’s dementia charity, the Silviahemmet foundation.

After some thought the pair decided to spend the money on designing affordable ready-built housing for older couples that could be easily adapted to their needs if one of them were to develop dementia.

Plans for Scandinavia and the U.K.

They approached BoKlok, which has built about 12,000 prefabricated apartments aimed at young families on a tight budget in Sweden, Norway and Finland, and is preparing to construct 150 timber-framed eco-homes in Worthing, West Sussex.

The units come with one or two bedrooms and are intended to cost no more than $1,950 a month.

The result was SilviaBo (“Silvia-living”), a line of flats that are built in a factory, complete with all their furnishings and an Ikea kitchen suite, and then dropped into place on the building site.

Together with the plumbing and electrical wiring, the whole process of assembling a unit of seven or eight flats in situ is meant to take less than a week.

The basic apartments, which come with one or two bedrooms and are intended to cost no more than $1,950 a month, are built in blocks of between two and four floors around park-like communal gardens with flowers and fruit trees and “village greens” for picnics and barbecues. Each is subtly adapted to the needs of older people, with automatic doors and wide entrances to accommodate a wheelchair.

Should one of the residents have dementia diagnosed, the flat can be upgraded with an adjustable wash basin, knobs and heat sensors on the ovens, and an alarm button in the bathroom.

The apartments are built in blocks of between two and four floors around park-like communal gardens with flowers and fruit trees and “village greens” for picnics and barbecues.

At Queen Silvia’s instigation, the height of the shower screens has been fixed at 1.2m so that a carer can bend over the side to wash their charge without getting splashed. She also insisted that each bedroom have a door opening directly into the bathroom to cause minimum confusion to dementia patients waking in the night.

Each is subtly adapted to the needs of older people, with automatic doors and wide entrances to accommodate a wheelchair.

Mr Spangenberg, 57, said Queen Silvia, 76, the country’s longest-reigning queen, had been more closely involved in the project “than we could have dreamt of”.

“She really saw how it can be to have a spouse or a parent who gets these kinds of symptoms or illnesses,” he said. “She provided us with pictures of the solutions that she had invented in her own home because she was sick of getting wet when she tried to help her mother take a shower.”

BoKlok is holding talks with the local authorities in Bristol and Swindon over building standard apartments in the UK.