Hawker Hunter down at Shoreham
If one takes the graphic as approximately correct,then the intent of the manoeuvre is to change the heading of the aircraft through about 40 degrees to line up with the display line. A loop leaves the aircraft on entry heading and a quarter clover will change heading through 90 degrees. The is however nothing to stop the pilot intentionally modifying a quarter clover to roll out on the intended heading. In fact if you look at the lateral profile that the manoeuvre achieved it would have left the aircraft neatly placed relative to the display line but for the last few seconds.
I agree with an earlier poster that the aircraft appeared to spend too much time in the vertical pointing downwards, whether this was due to a problem or lack of energy I don't know.
If as mentioned earlier in this thread if there was a airspace cap of 5500 feet then this and other manoeuvres would be more challenging to fly.
Essentially, pulling through from inverted requires a reasonably narrow gate of minimum and maximum speeds together with a minimum height. If airspace is not a problem then you can built in a decent safety margin and take excess energy into the manoeuvre, if you are not yet slow enough at the intended altitude for the pull then you may continue upward until you are at the correct speed. It's then possible to use a more graduated pull between the vertical and level, controlling speed with power or speed brake.
If there is a maximum altitude available then one variable in the "total energy" equation is removed giving less flexibility when dealing with any unexpected problem.