The Head of the Border Force, Brian Moore, said that our border controls were generally very efficient.
The Border Force expects most British or European nationals to travel through passport control in 25 minutes or less, and most foreign nationals within 45 minutes.
But occasionally, disruption is caused by issues like flight bunching, where several flights arrive at the same time.
He added: "Occasionally there is some disruption to travelling passengers, which we regret. But we all want a safe United Kingdom and a strong border."
More top news
The weapon was found by a member of the public in bushes in Greenford.
Production on the sixth film in the franchise, M:I 6: Mission Impossible, will be put on hold while he recovers.
The horse suffered a broken leg when it was hit by a HGV lorry and had to later be put down at the roadside.