Are you allowed to bring a metal flask (0.5l) with (warm) baby food inside through the security on the airport? I am flying internationally from London Luton and returning from Warsaw, Poland.
It should be Ok
You are allowed to take baby food, baby milk and sterilised water in your hand baggage...
You are allowed to take enough for the journey. In some cases this may be over 100ml. The adult carrying the baby food or milk may be asked to verify it by tasting.