Almost all general medical practitioners (GPs) in the UK use computers, compared with less than one in ten of hospital doctors. This paper explains how this unexpected situation came about over a thirty-year period, identifying some of the successes and failures of British medical computing along the way. Twelve separate factors are considered. The major determinants have not been technical, but rather a strong tide of political backing for general practice and leadership from the profession at the highest level, which have combined to build an appropriate regulatory framework and financial incentives that have encouraged GPs to embrace computers. Hospital computing has some difficulties not met by GPs, but the main factor preventing progress has been the lack of any real incentive positive (carrot) or negative (stick), for hospital doctors to use computers.