So this is what life is like for the musicians providing the music for a West End show. In a show like Hamilton, which is through-sung (i.e. there is no spoken dialogue), the musicians are playing all the time during the show. This is a feat of concentration and musical stamina, especially when there are 8 performances every week.
Notice a few things about the technology they are using: their sheet music is on big iPad-like screens where pages will turn automatically or with a foot switch. The keyboard player has different things plugged into their keyboard which gives them the ‘patches’ or different sounds they will need.