In this paper we introduce ukWaC, a large corpus of English constructed by crawling the .uk Internet domain. The corpus contains more than 2 billion tokens, is one of the largest freely available linguistic resources for English. The paper describes the tools, methodology used in the construction of the corpus, provides a qualitative evaluation of its contents, carried out through a vocabulary-based comparison with the BNC. We conclude by giving practical information about availability, format of the corpus.