Freelander 1 TD4 clutch master to slave hose clip, how?

I am trying to replace the master slave on SWMBOs FL1 TD4. It's all really simple except that I cannot separate the two pipes at that clip in joint.

It moves around a bit and will twist, but it just will not pull out.

I even thought of unscrewing the connector barrel from the slave cylinder pipe so that I can mess with it on the bench or buy a new one, but the nut seems screwed into that barrel mega hard.

I managed to extract the white plastic collar bit but after 90 mins trying the separate the rest :-(

Is there a special trick or is that it just needs a lot of force to pull it out?

ok I figured it out. Actually the plastic collar is what releases it. You have to ram the white plastic into the barrel hard and this releases something inside.