Tapered toilet spigot

[Degs]

Does any one know how to fit the flexible waste pipe to a tapered spigot without it backing off, local merchant says you need tapered flexi and a jubilee clip, but still backs off. If you Google the only recommendation is to put some thing behind the pipe to stop it backing off. I'm sure this isn't the right answer.
Degs

 

[Chalked]

This will do the trick. Make sure the spiggot is clean and no lubricant.