Lawyers last night warned the blunder at the heart of the breast cancer screening scandal will cost the NHS millions of pounds in compensation.
They are expecting those families affected to launch a 'huge legal challenge' against the health service.
After Health Secretary Jeremy Hunt promised compensation to families who lost a loved one as a direct result of the error, payouts are expected to range from £65,000 to £1million.
Between 130 and 270 women are feared to have died as a direct result of missing screening invitations due to the 'devastating' IT glitch.
Trixie Gough (pictured) died of breast cancer just before her 76th birthday. After news of the screening scandal broke today, her husband Brian said he was 'gobsmacked' and knew 'straight away' his wife, pictured, had not been given the scan
But many others may have had to endure unpleasant treatment and surgery because tumours were diagnosed late.
Maria Panteli, partner in the clinical negligence team at the solicitors Leigh Day said: 'It is no surprise to learn that a failure to invite these women to their final scan meant that hundreds of lives were affected with many tragically shortened.
'The Government now faces a potentially huge legal challenge on behalf of thousands of women, and their families, which could cost millions of pounds in compensation for those whose lives have been ruined by these failures.
'The announcement of an independent inquiry is to be welcomed, but it must be soon and it must be rigorous.
The breast cancer scandal was only discovered thanks to an Oxford University trial into extra breast cancer screening for women.
The AgeX trial was set up in 2009 to find out whether cancers could be diagnosed with extra screenings ‘without undue harm’ in those aged 47 to 49 and 71 to 73.
Around 65 breast cancer units across the country then recruited women from these age groups with the computer programme supposed to select half at random to be given the extra screening.
But a computer glitch that was in the system from the start of the trial meant a large number of the older group had scans cancelled without ever knowing they were going to be arranged.
Once the Oxford researchers discovered the error, it soon emerged that the same mistake had affected women in the entire screening programme.
'It needs to looks at all the reasons of how such a tragedy could have happened and be absolutely sure in its findings that, with so many lives at stake, it couldn't happen again.'
Olivia Mitchison, senior solicitor at the negligence solicitors Bolt Burdon Kemp said: 'This is an example of an unacceptable administrative error which may have had fatal consequences.
'If shown to be the case, this could lead to many medical negligence claims and cost the NHS thousands in compensation. Patient safety must be the top priority for the NHS.
Mauveen Stone (pictured with husband John) , who was diagnosed with breast cancer in August, claims doctors said she had 'slipped through the net'. She too may be eligible for compensation
A trial designed to see if extending the age range of breast screening reduces deaths from breast cancer may unwittingly have led to women dying unnecessarily from the disease.
The Oxford-led study, called AgeX, was set up to test whether it would be beneficial for women aged 47 to 49 and 71 to 73 to routinely be offered screenings.
Backed by Public Health England and the NHS Breast Screening Programme, it has been taking place in 65 breast screening services across England. It is thought that the computer glitch which caused the error was programmed into the system at the start of the trial in 2009 and ran through to 2018.
The algorithm randomly selected half of women in the additional age groups to be screened for cancer and half not to be.
But the program appears to have cancelled the last routine scan women in the older group should have had before their 70th.
As a result, it is thought that many women aged between aged 68 and 71 during that period did not have their last mammogram.
While those assigned extra screening will have been checked, those in the control group are the 450,000 women who missed out.
Women are currently invited for routine screening every three years between 50 and 70, although people over this age can request to continue screenings.
'These women have been let down and put at risk because of this administrative error. This has the potential to lead to a class action.'
GPs yesterday warned that they would be inundated with worried patients trying to find out what to do next.
Health officials are in the process to writing to the 309,000 women affected by the scandal who are still alive and living in the UK.
Those who are aged 70 or 71 will be encouraged to have 'catch up' screening. But if they are 72 or older, however, they will face an agonising choice as to whether to have the mammograms.
At this age there is a risk they will do more harm than good by picking up slow-growing tumours, which then have to be surgically removed.
Professor Helen Stokes-Lampard, chairman of the Royal College of GPs, said: 'We are shocked to learn that hundreds of thousands of women in England have missed out on their opportunity for breast screening – and the implications for GPs and our teams will potentially be significant, as patients seek reassurance and to find out where they go from here.'
Patricia Minchin (pictured) was diagnosed with breast cancer two years after she failed to get a letter for her final routine breast scan. She could potentially get a hefty payout
Up to 450,000 women, now aged 70 to 79, may have missed out on their final routine breast screening. This is what will happen next.All women affected who are registered with a GP will be informed by letter from Public Health England by the end of May 2018.Women affected aged up to their 72nd birthday will receive a letter inviting them for a catch-up screen.Those aged 72 and older will be able to contact a dedicated helpline to discuss whether a screen could benefit them.Women, aged 70 to 79, currently registered with a GP, who do not receive a letter from PHE can be assured they are not affected and do not need a catch-up screenIf you are not registered with a GP and believe you did not receive an invitation for a screen sometime between your 68th and 71st birthday call the below helpline.Women are advised to be aware of any changes to their breasts and see their GP if they have any