Marc works primarily on the study of words, meaning, and effect in English, usually using the Historical Thesaurus of English, cognitive linguistics, or approaches from the digital humanities.
He is the third Director of the Historical Thesaurus of English, following Professor Michael Samuels and Professor Christian Kay. He was Principal Investigator of the AHRC/ESRC-funded SAMUELS project (Semantic Annotation and Markup for Enhancing Lexical Searches, 2014-15) project, which used Thesaurus data to annotate words in text with their disambiguated meanings in order to open up new ways of digitally analysing language, and was also a co-investigator on the three-year AHRC-funded Mapping Metaphor with the Historical Thesaurus project and the AHRC-funded Linguistic DNA of Modern Thought project (Principal Investigator Professor Susan Fitzmaurice, University of Sheffield), and the AHRC-funded Hansard at Huddersfield project (Principal Investigator Professor Lesley Jeffries, University of Huddersfield). He created the Hansard Corpus 1803-2003 and has worked with Hansard editors in the House of Lords on the analysis of parliamentary discourse and style. In addition to the corpus discourse of Parliament, I also work on legal English and the linguistics of statutory and constitutional interpretation.