Stumped by Heating System Low Point Drain Design

[Alistair803]

I want to drain the heating system in order to flush and re-inhibit it.
I had a look at the low point drain and am confused as to how to operate it.
The drain on my radiator valve has a combined outlet and "drain bolt" - see photo.
In other words, you don't appear to be able to open the drain valve (get access to the drain bolt) with a hose connected to the drain point.
What am I missing? Is there a special tool required?
Why would anyone fit such a stupid design of drain point?
I can only find one such valve type on Google (Myson Matchmate 2) and there is no description on how to operate it.
Any help would be appreciated.

 

[terryplumb]

Close the radiator valve ,use a key ( like you use to bleed a rad) to loosen / remove the drain cocks square ended shaft. Fit hose ,then open the radiators valve.