A shining ball of light , brightness of a star (which i thought may be aircraft landing lights as it was coming directly toward me) about the same size or mass as a bus

ufo inclined to the left at approx level of clouds estimation 1000ft but relatively clear night scattered, when it passed through a cloud it seemed to give off a red light as if searching or scanning it lasting about 5secs the light was not a narrow beam but resembled a triangle or segment. The ufo headed West and gathered speed toward a jumbo jet

The jet was heading West and was very visible and about 4/5 miles away and climbing as London airports about 20 miles South and would estimate this jet was one of our biggest. Ufo followed behind jet then manouvered to the side of the jet for about 5secs i remember being worried that the object was on a collision course and who would i call first police RAF Airport, then the ufo went to the front of the jet then sped off at high speed to the North in my opinion i believe the pilot must have seen it but how would i find out as i can imagine they might keep it hidden for a while. Can i call the Airport? Also when i got to work i mentioned it to a friend and he confirmed a similar sighting an hour before