Chemtrail question.

If i have any credibility in this world i know i'm about to ruin it, however....

I admit to watching the UK's reality tv show Big Brother. Don't ask me why as they are the usual annual bunch of nutjobs. I think i'm correct in saying the Big Brother house is either near or under a major London flight path, and a couple of days ago i was watching an episode and in between clips they showed what appeared to be a large passenger jet flying overhead. Out the back of this plane was the biggest amount of smoke and crap i've ever seen! I think it was four trails of thick white smoke, definately more than i've ever seen coming from the back of a plane before.

I know a lot of people dismiss the whole chemtrail thing, which is fair enough, but could anyone with knowledge of aircraft tell me what this may have been? I'm not in the habbit of watching planes around airports so i'd love to know whether this is normal for low flying planes?

I'm kind of hoping it was some kind of chemical, it would certainly explain the housemates behaviour recently!

Thanks,

CX.