So I recently made a return journey from London Southend (SEN) to Dublin (DUB), flying out of SEN and into DUB on Saturday on Aer Lingus, and back to SEN on Sunday via a similar Aer Lingus flight. In Dublin I did have to go through passport control (I received a stamp because I am non-EU).
But on the return flight back to SEN there was no immigration control at all (like a domestic flight). Was this some mistake?
I also asked another friend who had flown back from DUB to London Standsted (STN) and although they did have immigration control, there was a separate "Entry from Dublin" line which bypassed most checks, again my friend is non-EU.
So was this just a mistake? Or does the UK accept entries from Dublin/Ireland and just trust everyone coming in?