Despite this, the supply of contaminated blood was not stopped until 1986.
The contaminated blood scandal of the 1970s and 1980s centred on the use of clotting agents for patients with haemophilia.
Charles, 68, looked intently at the frothy pint of Swelkie Golden Ale, which is made on the premises, before taking a sip from the glass.
He has also visited the Captain's Galley seafood restaurant in Scrabster and viewed the Society of Artists' exhibition at Thurso High School.
Newly unearthed minutes of meetings held in 19 show that officials consciously put patients at risk during a scandal which killed 2,000 people.
Dr Howard Thomas, a liver expert, told the meeting: 'It is in ten years' time that we shall see the problems.'Bearing in mind the proportion of the patients that are infected, or have persistent abnormal liver function tests – anything from 60 to 80 per cent – it will be an enormous problem when it happens.'Dr John Craske, a leading virologist, said he was particularly worried about 'non-A, non-B hepatitis' – a disease which eventually became known as hepatitis C.
He told the meeting: 'There is a high risk from the use of Factor VIII or IX concentrate that the patients will contract non-A, non-B hepatitis, and a 20-30 per cent chance of resultant chronic hepatitis.'Nine months later, in June 1981, the Government's blood transfusion research committee met in London.
Scientists were so sure the blood was dangerous, they even planned to use victims as guinea pigs to develop a new test for hepatitis, say the papers, which are likely to play a central role in a major civil action to be lodged at the High Court today, in which 300 families of victims are suing the Government.
The minutes show officials knew at least 50 patients a year were becoming infected with hepatitis.