Interesting craft in te sky?

Ok, I don't usually make posts like this. Why? Because they sound dumb
And I hope I didn't get your hopes up with the title either

Like, I read one the other day where someone and his dog were in an empty car park and made contact with Grays........Right.....

Anyhow, I live near Gatwick Airport in the UK. Its a commercial international Airport.
I live about 8miles away, but I'm still under one of the main flight paths for Europe.

I work from home and I sit under a window, so I'm constantly seeing planes flying over... So I KNOW what they look like

Anyhow, the other day something flew over head that was flying slightly lower then normal, very fast , no sound and the contrail was non existent.
Well, it was there, but disappeared with in seconds. It didn't linger for any real amount of time like other plane trails do.

I'm not sure what the flying altitude is for planes just taking off in my area, but usually I can make out something, like the colour of the tail... To indicate which carrier it is etc.... But at the least, I can make out that it is an aircraft.

Now I'm probably over reacting, it probably was a plane.... But I don't know, it seemed rather odd....

Of course, I don't have any proof of this, picture etc, just an account of what I saw. I did try to find my binoculars, but by the time I had focused them, the object was gone....

So did I see a plane or something else?

was it 2 blinking yellow/whitish lights?
I saw 2 days ago something weird in the sky, 2 yellow/whitish lights blinkingm it went fast
it was dark outside, i tried to take a picture of it but it went to fast i couldt zoom on it.

It could be a plane, but it had no green or red light
just 2 yellow whitish lights, and it went very fast.

Nope, this was during day. Sometime between mid day and 2pm.

As far as I am aware, the wingtip/ hull safety lights don't flash during the day.. Ill happily stand corrected though.