I and many others have arrived at T5, gone through immigration, walked through customs with hand luggage only, taken the lift from the Arrivals Level to the Departure Level and gone through security again from landside?

Why? The security queues on the South side can be shorter than the security on the North side when there are loads of pax transiting T5 in the morning.


Likewise, you can go from T5 to T3 landside if you wish instead of using the airside bus transfer with no need to clear immigration.

My view is that the T3 transit security queues are usually shorter and no where near as chaotic of the T3 landside security. The choice is yours provided you have no issues clearing UK immigration. Reason for immigration entry into the UK. Meeting a relative landside for in transit in the UK is one but a more likely reason - for a chance to smoke outside the terminal during transit. There are no smoking rooms indoors in the UK, including all airport terminals.