A normal flight schedule has been operated at Terminal 5 since Tuesday, but BAA have put back the date of the long haul transfer to ensure that high service standards are maintained when additional flights are introduced.
They will be using the extra time to iron out any remaining problems, including the baggage system and its operation and to develop a robust timescale for phasing the move of Terminal 4 services into Terminal 5.
BA’s Chief Executive, Willie Walsh said: "We are making this decision in the interests of customers. Though Terminal Five is now working well, we need to have confidence that good service can be maintained when the terminal is handling larger numbers of customers.
"It is only sensible to ensure that Terminal 5 is operating consistently at a high standard before the move begins.”
BAA’s Chief Executive, Colin Matthews said: "BAA regrets this postponement, and we recognize the impact it has on other airlines, but we believe it is a wise precaution to ensure that passengers can have the maximum confidence once the move does take place.
"We will be working very closely with BA in the intervening period to ensure that result, as well as working with the other airlines to mitigate as much as possible the knock-on effects.
"BAA fully recognizes that the inauguration of Terminal Five has not been as smooth as we and BA would have wished. In the last few days passengers have seen significant improvement and our goal is to complete that process as soon as possible before continuing the next phase of transforming the rest of the airport."