BUT THEY DID MAKE COMPLAINTS!
This is a huge part of the Gregg Wallace issue.
It's not just Gregg himself. It's those that didn't act further.
It's something almost like the bystander effect:
https://en.m.wikipedia.org/wiki/Bystander_effect
Once a situation has been noticed, a bystander may be encouraged to intervene if they interpret the incident as an emergency. According to the principle of social influence, bystanders monitor the reactions of other people in an emergency situation to see if others think that it is necessary to intervene. If it is determined that others are not reacting to the situation, bystanders will interpret the situation as not an emergency and will not intervene. This is an example of pluralistic ignorance or social proof. Referring to the smoke experiment, even though students in the groups had clearly noticed the smoke which had become so thick that it was obscuring their vision, irritating their eyes or causing them to cough, they were still unlikely to report it. Only one participant in the group condition reported the smoke within the first four minutes, and by the end of the experiment, no-one from five of eight groups had reported the smoke at all. In the groups that did not report the smoke, the interpretations of its cause, and the likelihood that it was genuinely threatening was also less serious, with no-one suggesting fire as a possible cause, but some preferring less serious explanations, such as the air-conditioner was leaking. Similarly, interpretations of the context played an important role in people's reactions to a man and woman fighting in the street. When the woman yelled, "Get away from me; I don't know you," bystanders intervened 65 percent of the time, but only 19 percent of the time when the woman yelled, "Get away from me; I don't know why I ever married you."
You almost have a situation where sexual harassment is so normalised no one wants to break rank. They don't want to intervene and they don't see It as their responsibility - it's always someone else's.