Actually, the Guardian is as usual making much ado about nothing. It was ALREADY known than Mussolini was paid by Hoare—Hoare mentioned it in his memoirs. Prior to the British payments, Mussolini pocketed French secret service money. And the Brits hardly gave Mussolini his “start”. Mussolini was a prominent Socialist politician before WWI started.
It’s the details of the payments/amounts that are news.
And don’t forget the Germans helped Lenin get into Russia in 1917. Doesn’t mean Lenin and the Kaiser were pals.