Experts knew HIV was spreading through patients given infected blood products years before they came clean about the scandal.
New documents have emerged as Professor Christopher Ludlam is set to face questions at the inquiry into the contaminated blood scandal this week.
A colleague at the Haemophilia Centre has previously denied they knew of the extent of the problem in 1984.
But nearly unearthed documents show it was discussed at a meeting attended by the centre’s top medic.
More than 4,000 people were infected with Hepatitis C and HIV in the 70s and 80s through Factor VIII, designed to help haemophilia sufferers’ blood clot, and at least 1,500 have died as a result.
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Patients and families say that doctors knew they were infected with HIV but were not told, sometimes until years later.
Former Prime Minister Theresa May announced a UK-wide inquiry in 2017, which is currently ongoing.
Earlier in the inquiry into the scandal and alleged cover-up, Haemophilia Centre director Dr Mark Winter claimed it was not clear by 1984 whether patients carrying HIV antibodies had the disease and could spread it.
Dr Winter, who in September was the first doctor to give evidence, said medical opinion was split in 1984, and some believed a positive HIV test could mean patients had only been exposed to a dead form of the virus.
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But previously unseen documents due to be submitted to the inquiry by campaigners this week reveal this was untrue.
Papers from a November 1984 meeting attended by Professor Ludlam, head of the organisation, say “It is important to appreciate that patients with antibody are infectious and can transmit the virus”.
Lauren Palmer from Bristol lost both of her parents to HIV in 1993 when she was just nine years old.
Factor VIII infected her father which was then unwittingly passed on.
Lauren said: “Some of the doctors are saying that they didn’t know what the HIV test meant, but it’s clear from this document that Professor Ludlam and others did know.
“I just want them to tell the truth. It’s obvious now that they’ve known this for over thirty-six years and have been playing it down, it’s outrageous, it’s time for people to come clean and admit who knew what and when.
“If my parents had been told what was known as soon as it was known they’d still be here today.
“The negligence of patient care has destroyed my family, having to grow up without my family has been devastatingly traumatic and still affects me to this day.
“I just hope the Inquiry can bring some justice for my parents, make those responsible accountable for their actions and above all uncover the truth.”
Des Collins, senior partner of Collins Solicitors, which represents 1400 victims and families affected by the Infected Blood Scandal, said: “Ludlam is an important figure giving evidence to the inquiry.
“We need all those who were complicit in this scandal, either wittingly or unwittingly, to give an honest account of what they knew at the time, the procedures followed and critically what questions were asked of the NHS’ approach.
“After some 40 years the infected and affected deserve to hear the truth from those in charge whom patients respected and trusted with their health.
“We look forward to hearing Professor Ludlam’s testimony this week, especially his explanation for the lack of transparency that we know existed.”
The revelation comes after we reported earlier this year that Professor Ludlam told public health chiefs a medic convicted of lying about HIV-infected blood was a man of “high integrity”.
Professor Ludlam said Dr Jean-Pierre Allain should keep his job in a letter to the head of the UK National Blood Authority.
It came after the Frenchman, who was director of the East Anglian Regional Blood Transfusion Service, was convicted.
Professor Ludlam declined to comment ahead of his appearance at the inquiry.
