Computer science in UK schools is undergoing a remarkable transformation. While the changes are not consistent across each of the four devolved nations of the UK (England, Scotland, Wales and Northern Ireland), there are developments in each that are moving the subject to become mandatory for all pupils from age 5 onwards. In this article, we detail how computer science declined in the UK, and the developments that led to its revitalisation: a mixture of industry and interest group lobbying, with a particular focus on the value of the subject to all school pupils, not just those who would study it at degree level. This rapid growth in the subject is not without issues, however: there remain significant forthcoming challenges with its delivery, especially surrounding the issue of training sufficient numbers of teachers. We describe a national network of teaching excellence which is being set up to combat this problem, and look at the other challenges that lie ahead.