Contact the noise complaints dept at LGW, they'll need the date time, location of the event. They can then use their noise and track keeping system to identify the event, they do this by overlaying radar tracks onto a geographical database. I don't know their specific policy but they may be able to supply some details, and maybe if this has had any follow up on the airport operator part eg noise penalty fine. I don't think however they will identify the operator.
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