A surprisingly small number of innovative firms use the patent system. In the UK, the share of firms patenting among those reporting that they have innovated is about 4%. Survey data from the same firms support the idea that they do not consider patents or other forms of registered IP as important as informal IP for protecting inventions. We show that there are a number of explanations for these findings: most firms are SMEs, many innovations are new to the firm, but not to the market, and many sectors are not patent active. We find evidence pointing to a positive association between patenting and innovative performance measured as turnover due to innovation, but not between patenting and subsequent employment growth. The analysis relies on a new integrated dataset for the UK that combines a range of data sources into a panel at the enterprise level.