4xSmall Plane Formation - 35,000 ft

[hammo19]

Around 11:55 this morning 4 contrails, small jets, in arrow formation heading North at probably 35,000 feet over North Sea coast Durham/Sunderland area. Not on FR24 or Military Radar.

Anyone any ideas? This is the place someone would know.

[hammo19]

Looks like F15s then - thanks chaps