Generative AI and large language models (LLM) are considered in many industry and service sectors as promising technology for automating routine tasks. The potential of LLM has also been noticed in the area of consulting services, but there is not much work in the scientific body of knowledge. With a focus on IT consultancy (ITC), the paper aims to contribute to a better understanding of how LLM can be applied from the perspective of the consultants. An interview study with two interlinked series of interviews, in total 20 experts in IT consultancy and AI experts, is conducted. The main contribution of our work is (1) a systematic literature analysis of LLM use in IT consultancy, (2) results of two series of expert interviews, and (3) a feasibility study of LLM use in an ITC activity considered by the interviewees as a time-consuming and promising area for LLM usage. The findings of the study indicate the substantial potential of LLM in ITC for automating or increasing the efficiency of a number of tasks, but, so far, no substantial changes in ITC value creation processes.