THE start of an inquiry into the contaminated blood scandal which left at least 2,400 people dead is a day few thought they would never see, a solicitor representing hundreds of victims said.

It will consider the treatment of thousands of people in the 1970s and 1980s who were given blood products infected with hepatitis viruses and HIV, and the impact this had on their families.

Seven-year-old Colin Smith, of Alway in Newport, died of Aids in 1990, having received contaminated blood products several years earlier to treat his haemophilia.

It was later discovered that he contracted HIV and hepatitis C after being given the clotting protein Factor VIII, which had come from a prisoner in an American jail.

One of the people at today's enquiry was his mother Janet.

Mrs Smith and her daughter-in-law Laura Smith appeared on the Victoria Derbyshire show this morning where they spoke about Colin and the difficult time they had after his death.

At the opening of the public inquiry into the contaminated blood scandal, Downton Abbey actor David Robb, and actress Isla Blair spelt out the figures, facts and impact of it.

Testimonies from those infected and affected by the contaminated blood scandal, spelling out the life-changing impact of it, were also shown to the inquiry.

Emotional video accounts lasting more than half an hour described the toll on all aspects of their lives as they spoke to the camera.

After a poem called Making A Difference was read by Lemn Sissay, those infected or affected by the scandal approached the front of the stage clutching tiny bottles.

Each one, that was clear and clinical in appearance, contained a private and personal message, and was placed into a wire shelving unit in front of the audience.

Retired judge, Sir Brian Langstaff, chairman of the inquiry, addressed the hundreds who had attended the start of the Infected Blood Inquiry.

The former High Court judge said he would rather that no one had any need to attend the probe, and that what has been described as a tragedy and catastrophe had not happened.

Sir Brian told the inquiry in London on Monday: "The numbers here today pay a silent testimony to the sheer scale of the tragedy.

"It is a truly sobering thought that if some of the claims are well-founded - and it is for this inquiry to find out if they are - there may yet be many thousands more who do not feel well, but have not yet been told that the reason for this is that their life is threatened by Hepatitis C."

Sir Brian said it is estimated that the number of deaths could go far beyond 2,500, adding that there is a "real chance that these estimates may prove right".

Sir Brian also said the inquiry will be UK-wide and will not confine itself to London - with the aim to conduct hearings all over the country to enable more affected people to come in person.

With allegations of a cover-up which he said will be investigated, Sir Brian stressed that the probe will be as "open and transparent as it is legally possible to be".

During her opening statement, counsel to the inquiry Jenni Richards QC, said the terms of reference were a product of public consultation, describing it as a "moving, humbling, and enlightening process".

"The inquiry does not underestimate the scale of the task which it faces," she told the packed room.

"It recognises that this is an immense undertaking which will require an enormous amount of work.

"It is immense because of the breadth of the issues that are encompassed within the terms of reference. It is immense because of the periods of time that are under investigation.

"This inquiry is looking not at events that unfolded over minutes, hours, days, weeks or even months, but at actions and inaction, conduct, decision making, policy making over decades."

Ms Richards said the scale of the task is also immense because of the amount of documentary evidence which the inquiry is likely to receive - with 100,000 documents already in their possession - a figure that she said will likely grow.

She also revealed that to the best of their knowledge the inquiry currently has the largest number of core participants of any public probe - with 1,288 already involved of which 1,272 are affected or infected individuals.

Alongside eight charities and campaign groups as core participants, Ms Richards said there are also three government departments which are too.

These are the Department for Health and Social Care for England, Department for Health Northern Ireland, and the Health and Social Services group of the Welsh Government, she said.

Ms Richards said the Scottish Government is not currently a core participant because it believes that the inquiry should not revisit issues already addressed by the Penrose Inquiry.

She added that is very likely the number of core participants "will continue to grow".

Ms Richards said the intended start date to begin hearing evidence is April 30 next year. She revealed they will aim to sit three weeks out of every four, and up to four days a week.

The public probe will hear from those affected and infected first, and that this part of the inquiry will last through May, June and July, she told those gathered.

Ms Richards also said they are not able to currently give a reliable answer as to how long the inquiry will take, but that the process will not be under a year-and-a-quarter.