BlackBerry will have fewer than 1 million users outside businesses in the UK by the end of the year, a radical slump from a peak of nearly 8 million in June 2012, according to new research from two companies.

The dramatic fall from grace of the iconic mobile phones, which were blamed for spreading unrest during the London riots of summer 2011, follows a series of high-profile and expensive flops — first with its PlayBook tablet and then with the touchscreen Z10 phone, as it tried to catch rivals such as Samsung and Apple.

The firm has also plunged into operating losses and seen revenues dwindle for 11 of the past 12 quarters. In a bid to cut costs, it has fired thousands of staff.

Now new research from eMarketer provided exclusively to the Guardian paints a bleak picture for the company. It says it may have as few as 700,000 non-business users in the UK, and that by 2017 the figure could fall to 400,000.

These latest figures show that even its previously loyal core seems to be leaving in droves Bill Fisher, eMarketer Separately, another research company, Kantar Worldpanel, told the Guardian that although BlackBerry’s data currently shows 1.4 million non-business users, it is losing 56,000 users every month to other platforms such as Apple’s iPhone, Google’s Android and Microsoft’s Windows Phone. “I’d expect we would see fewer than a million people with a BlackBerry as their primary handset around September 2015,” Dominic Sunnebo, global consumer insight director at Kantar, said.

The UK used to be one of BlackBerry’s biggest and most loyal markets — but the collapse in consumer base will create financial problems for the company, which under its new chief executive John Chen has retrenched to its original corporate and government roots, where it is prized for its levels of security. But both Apple and Samsung have begun to make inroads there, winning approval from the US and UK governments for their handsets to be used in low-level security work.

BlackBerry’s revenues rely heavily on handset sales: Chen has said that it needs to sell 10m per year to be profitable. But falling user numbers mean fewer sales and a spiralling problem for the company.

“BlackBerry’s fall from grace has been spectacular, but these latest figures show that even its previously loyal core seems to be leaving in droves,” said Bill Fisher, UK analyst at eMarketer. “Its market share has been decimated by Android and iOS, and more recently by Windows Phone, which is slowly gaining a foothold in the UK market.” The company has not been helped by high-profile missteps, such as a software update last Thursday that left LadyTanni Grey-Thompson, the paralympic medallist and parliamentarian, bemoaning the random shuffling of her contacts book. She has threatened to dump BlackBerry for another maker.

BlackBerry had not responded to a request for comment by the time of publication.

Among UK smartphone users, Google’s Android makes up 56.2%, comprising 21.5 million owners, says eMarketer, while Apple’s iPhone has 12.3 million users, or 32.2%. Microsoft’s Windows Phone has 3.3 million users, or 8.5%, and BlackBerry’s sub-1 million users make up just 1.9%. Kantar puts Apple’s figure higher, at 13.4 million (38.1%) and Android’s lower, at 17.4 million (49.6%), with Windows Phone users totalling 2.3 million (6.5%).

Sunnebo said the shift pointed to wider challenges in the phone market. “What this does mean is that ‘easy wins’ in the UK market are coming to an abrupt end. With only 2.1 million customers of old platforms like BlackBerry, Palm, [Nokia] Symbian and [Samsung] Bada left, brands can only really win significant numbers of new customers from consumers already using modern, competitive platforms.”