This is not a matter of life and death, more an intriguing phenomenon. I am not saying that it is only related to this particular flight or that it is not, as I have done no serious analysis.
Sorry, but did not note the flight details at the time, but looking at my log, it was probably F100 HB-JVH, I think going from Manchester to Zurich.
The reason that I noticed it is because I saw on my own system that it was going overhead and, as the Radarbox24 Elite data was coming from my box, I went outside with my phone and found they did not match. I do not make a habit of using both simultaneously.
I would have to do a lot more checks to see if this is a one off, or maybe there is a time-space distortion in my village.
Thanks for the interest folks. I thought someone cleverer than me would know the answer.