Originally Posted by
KARFA
Do you mean connect through LHR to another UK airport? You would still do immigration at LHR even if connecting onwards on a domestic flight.
But must be a through ticket to start with unless you can persuade them to join your booking. That is a separate subject - but whispering .. we have been 100% successful asking at check in using CX ex Asian airports with the final U.K. Flight originating ex HKG.
That said it is usually a J Avios redemption in to HKG then a Y revenue ticket to MAN via LHR.