No-one has 'right of way'.
For blue car to move as indicated now is dangerous.
If I were in blue car and 'caught' in this situation (perhaps having just moved out of a slip, or perhaps the general traffic flow has been slow and is now clearing), I would look to brake to allow the amber car to complete it's overtake, then move out (assuming clear to do so) behind him to the outside lane and resume a 70mph cruising speed as the red 60mph car moved into lane2, thus leaving that bunching well behind and establishing clear space around me.
If I were in red car I would not be looking to move back to lane 2 until past the potential for conflict between amber and blue (and would accelerate to get away from it asap).
If I were in amber car I'd be worried about being blocked in both sides and would have been watching blue for some time, to see if (s)he was going to move out. Either I would have given blue room to do so (not moving alongside) or I would be traveling past with a significant differential (>5mph) once blue's chances of moving out was minimised.
Edit to add a thought from the M4 last night!
Perhaps the 56 and 60mph are because they are on a Managed Motorway with VSL in place!