The Health Protection Agency said the patient who died had an underlying condition that may have made him more susceptible to respiratory infections such as severe acute respiratory syndrome.
The first patient in this family cluster had recently traveled to Saudi Arabia and Pakistan and is still receiving treatment. The third family member, who had a mild illness, has recovered, health officials said.
Professor John Watson, head of the agency's respiratory diseases department, said since last September, when an earlier case was diagnosed in Britain there have been a total of 12 confirmed cases of novel coronavirus reported globally, with six deaths.
In total, the agency has identified and followed up more than 100 people who had close contact with the three recent cases from one family. Besides the identified secondary cases, all tests carried out on contacts to date have been negative for the novel coronavirus infection, Watson said.
"The risk of infection in contacts in most circumstances is still considered to be low and the risk associated with novel coronavirus to the general United Kingdom population remains very low," Watson said. "The HPA will continue to work closely with national and international health authorities, and will share any further advice with health professionals and the public if and when more information becomes available."