Triangle shape in the sky. The sun hit its surface which caused a flash, looked metallic.

Driving home from holiday in Devon. Sunny bright day with clear blue skies. See the object up ahead out of my front window screen. I thought at first it was a plane turning in the sky until I see it’s shape. It was triangular and the sun hit its metal surface causing a bright flash as it changed direction. I was watching it in shock as knew this definitely wasn’t a plane. I said to my wife “are you seeing this in the sky”. She replied yes what is it. As we started to discuss what we were seeing it totally disappeared without a trace. Very odd. It didn’t fly away it just physically disappeared without a trace.
I then made sure I logged the date and time and location so that I could report this. I would say I am experienced with aviation and other aircraft. It definitely was not like anything I have ever seen. It initially just seemed to be hovering before it started to turn. I am a serving police officer with Thames Valley Police.
It has taken me a few weeks to submit this report as wasn’t sure what to do with it.