I take it you are referring to having gone through security, into departures and arriving at the gate late - therefore missing the flight ?
This happened to me in LGW. I think it was around the time in question as it happens - but I havent checked. I was escorted from the the gate in the departure lounge, through the departures area (tracing back my steps), through someon doorways marked "no entry" and ultimately to a card access door which led to the area used for the UK border checks for inbound passengers. i.e i was taken from departures in to the arrivals area. The gate agent and I then walked to the front of the passport check queue and the border force officer was informed by the gate agent that I had missed my flight and she was escorting me to landside. I then had my passport and boarding pass checked by the border force officer and was allowed to pass through the area. The gate agent walked with us to landside where we left each other.
This was in North terminal & Easyjet / whoever handles them