A field experiment was conducted with a professional busker in the London Underground over the course of 24 days. Its aim was to investigate the extent to which performative aspects influence behavioural responses to music street performances. Two aspects of the performance were manipulated: familiarity of the music (familiar vs. unfamiliar) and body movements (expressive vs. restricted). The amount of money donated and number of people who donated were recorded. A total of 278 people donated over the experiment. The music stimuli, which was selected in an online study to differ only in familiarity, had been previously recorded by the busker. During the experimental sessions, the busker lip-synced to the pre-recorded recordings. Thus, the audio input in the experiment remained identical across sessions and the only variables that changed across conditions were the familiarity of the music and the expressivity of performed body movements. The results indicated that neither music familiarity nor performer's body movements had a significant impact on the amount of money donated (Rm 2 = .033) nor the number of donors (Rm 2 = .023). These results do not support previous literature on the influence of familiarity and performers' body movements, typically conducted in lab and artificial environments. The findings are further discussed with regard to potential extraneous variables that are crucial to control for (i.e., location of the performance, physical appearance, the bandwagon effect) and the advantages of field versus laboratory experiments.A novel research framework to study music judgements and behaviour is introduced, namely, the behavioural economics of music.