It was very easy to disconnect the top end of that pipe, unclip it and push it right down.
Water comes out of the head ok but not out of the pipe. I tried flushing and putting my hand over the ends, but it appears that an hydraulic lock and the thermostat? prevent the fluid from coming out. 2 litres was all that would come out hardly a flush and not enough to add 4litres of antifreeze.
I had to reconnect, refill with water and run the engine until the thermostat opened - not something I would reccomend so didn't write that above.
With the top of that hose disconnected I tried to disconnect the bottom end from above. I could squeeze the clips or pull, but not both! so I took the undertray off ( I hate doing that).
There must be an easier way of doing this - Anyone care to share?