what is this jet behaviour mean?

asking on behalf of a guy on another forum I am on I quote:

Today and yesterday, I have seen three fighter jets flying around the Essex Coast in the Mersea/Bradwell area. They generally were flying in tight formation over land and the sea. The colours are odd – one is red, one yellow and one orange. On one pass, they were accompanied by another aircraft – older, straight wings with pods on the end.

I’m not sure what they were doing, and I am bot able to identify aircraft, but they looked like modern jets. I could not make out any markings on them – though one had red/white/blue stripes on the tail (so RAF?).

Any ideas? It seemed unusual to me. No airshows here that I know of.

thought id post here to see if this kinda exercise? or something rings a bell to anyone?

edit: damnit cant edit thread title, worded it wrong…