Problem here, with the greatest respect, is that Luke f is a young person and possibly not an aviation professional and perkin does not reveal his details so we have to assume that he too is not an av prof.
It is a fact of life that the human brain is almost incapable of accurately assessing heights and distances. During my working life I fielded any number of telephone calls from pilots, ATCOs and other aviation-types who believed they had seen something "scary" aloft, ie two aircraft about to hit. In every case, the aircraft were legally separated.
It's no good us professionals TRYING to tell them otherwise... I escorted a group of anti-noise people round Heathrow ATC once. The rather stupid chairman told me in no uncertain terms that he was concerned about Heathrow inbound a/c flying down Windsor High Street at 5-600 feet. He would not accept that he was wrong. I showed him the SSR which proved that the aircraft were around 1,200 ft but he would not have it - claimed we had "fixed" the radar for his visit!!
This very day my wife and I came back from Jersey on a fast catamaran. We wathed two large ships through binoculars and were convinced that they were keeping very close station on each other - no more than yards apart. As our ferry turned north across the track of the ships we saw that they were actually a couple of miles apart!!
The only professionals I would ever believe regarding estimated heights are met observers. They can estimate cloud heights to a very high degree of accuracy. Everyone else....? No way Jose!
Don't forget what Father Ted said: "This one is small; that one is a long way away".