This paper describes Pickering, the semantic interpreter developed in the Higgins project - a research project on error handling in spoken dialogue systems. In the project, the initial efforts are centred on the input side of the system. The semantic interpreter combines a rich set of robustness techniques with the production of deep semantic structures. It allows insertions and non-agreement inside phrases, and combines partial results to return a limited list of semantically distinct solutions. A preliminary evaluation shows that the interpreter performs well under error conditions, and that the built-in robustness techniques contribute to this performance.