747400CA, LHR Approach ATCO.. .. .As far as I am concerned, anytime anybody declares a fuel PAN before or after LAM, I part the waves. He gets a direct heading to a comfortable length final and I move the traffic ahead of him out of the way. I consider this essential if he has declared a PAN because we are past the stage of being 'tight' and real danger exists. We don't know what else might go wrong (with flaps or gear for example) and his landing has to be safeguarded. . .. .If it was the case that moving the traffic out of the way was going to be impossible due workload etc. I would stop the outbound traffic and have the departure runway sterilised for him. We don't need the PAN to become a MAYDAY.. .. .I have firsthand experience of a single runway airport being blocked as I turned a seriously mishandling aircraft onto final at 13 miles. These things tend not to happen, so we come to think they can't. Once we have got to PAN, everything else has to be let go.. .. .As far as landing with a blocked strip is concerned: I offered the above traffic the taxiway - he turned it down sharply.. .. .Point 4