Dane-geld

 George Orwell, quoted by Nick Cohen.

Do remember that dishonesty and cowardice always have to be paid for. Don't imagine that for years on end you can make yourself the boot-licking propagandist of the Soviet regime, or any other regime, and then suddenly return to mental decency. Once a whore, always a whore.'

Or in the words of the dreadful old imperialist:

It is wrong to put temptation in the path of any nation,
For fear they should succumb and go astray;
So when you are requested to pay up or be molested,
You will find it better policy to say:—

“We never pay any-one Dane-geld,
No matter how trifling the cost;
For the end of that game is oppression and shame,
And the nation that plays it is lost!”
Kipling, Dane-Geld