A relative of the founder of the NHS died after two NHS trusts made serious errors during his cancer treatment.
Doctors diagnosed Roderick Bevan in 2016 while treating him for another condition but did not offer him radiotherapy for another 15 months.
Neglect contributed to his death, an inquest found, with his family saying his great-uncle Aneurin Bevan "would have been appalled" by his care.
Two NHS trusts apologised and said processes had changed after a review.
Mr Bevan, from Grantham in Lincolnshire, died aged 66 in May 2018 from lung cancer.
An inquest at Boston Coroner's Court, which concluded in May, heard a tumour was identified during a scan at Boston Pilgrim Hospital in October 2016.
Medical professionals at Pilgrim Hospital and University Hospitals of Leicester Trust, which later took over his care, did not tell Mr Bevan he had lung cancer until January 2018.
The narrative verdict recorded at his inquest concluded, on the balance of probabilities, the treatment proposed for Mr Bevan "would have been successful" if doctors had ensured he underwent stereotactic ablative radiotherapy.
Mr Bevan's daughter, Paula, said: "I feel that my dad was totally let down by the NHS, whose founder was Aneurin Bevan, who, as the name suggests, my dad was related to - it was his great-uncle.
"I am sure that he would be appalled by the events that have unfolded."
The two hospital trusts offered their "sincere condolences" to Mr Bevan's family.
Dr Neill Hepburn, medical director at United Lincolnshire Hospitals NHS Trust, said: "We accept there were opportunities for us to communicate more effectively with Mr Bevan and have carried out a full investigation into the circumstances of his death."
Andrew Furlong, medical director at Leicester's Hospitals, said: "Since our review we have made significant improvements to prevent this happening again."