The room above the courtyard

A local-history group had planned an evening talk in a ground-floor hall, but a burst pipe meant moving it to a room above the courtyard. Thirty-four places had already been confirmed; the new room contained 28 chairs, and its licence did not allow extra furniture. Three attendees had requested step-free access, but the lift was out of service and the only way up was a flight of stairs. Because of building work, visitors now had to enter through the side gate, although all the event notices remained beside the closed main doors. The talk was due to finish at 8.40 p.m., but the caretaker was required to lock the courtyard gate at 8.30 p.m.; this gate was the only route back to the street. The presenter also needed the room dark enough to show archive photographs, but its blinds had been removed and direct sunlight would remain at the windows until 8.45 p.m.

From this account, describe what may prevent the evening from running as planned. You may support your points with brief quotations.