Spiked! is not a left-wing outlet, libertarian or otherwise. They're a group of former doctrinaire Marxists who swung to the equally-doctrinaire libertarian right after the fall of the Soviet Union. There's a whole nexus of organisations around them, and they have made a good living out of being professional contrarians. Their influence in British politics has been nearly wholly malign, both when they were on the left and now they're on the right. They are excellent self-publicists. Their funding is probably the same US right-libertarian dark money pools as the Tufton Street groups, though it's hard to be sure as their finances are characteristically opaque.

Speaking as someone is is on the libertarian end of the British left, these guys are not our allies.