Johnson has repeatedly stated in clear and absolute terms that the NHS - which offers British citizens free healthcare at the point of access, regardless of illness - was not up for sale, but a 451-page internal government document, revealed by Labour leader Jeremy Corbyn, details a series of secret United States-UK trade negotiations covering a whole range of British public services - from food regulation to healthcare - to which Washington wants "full market access".
One detail suggests the UK would be open to longer patents on US-produced medicines, which Corbyn says would push up the price paid by the NHS for pharmaceuticals - perhaps by as much as 500,000 pounds ($645,000) a week.
Corbyn had challenged Johnson over the privatisation and sell-off during their first televised leaders' debate, waving a sheaf of heavily redacted papers covered in blacked-out text. On Wednesday, he said he had got hold of the unredacted version, which detailed six rounds of talks between US and UK trade representatives.
Al Jazeera's Paul Brennan reports from central London.
