You should have tried to resolve the issue then and there. Asked to speak to her supervisor, etc.

Where are you relative to LGW? Are you near the airport?
Do you have your passport back?

What do you have from easyJet regarding your denied boarding? Did they give you any documents?

You could consider making a report to the police about the photo bit. It is one way to get things taken more seriously! However that really is a separate concern.

What were you given about being denied boarding.
Do you have her name.