This sort of casual slander by association is so common that it goes unremarked. I've said it all before, and I won't repeat it all here, but it's clearly ludicrous to imply that National Socialism, with its glorification of an all-powerful state, is somehow a more extreme version of Lady Thatcher's belief in personal responsibility, private enterprise, and a smaller, less intrusive government .
It is obvious to any unbiased observer that Fascists and National Socialists are to the left of the political spectrum. They have much more in common with Old Labour and the BNP than with today's Conservative party.
But if you point this out, you're liable to be deselected as a Conservative candidate and fired from public office, as Rachel Frosh discovered.
Daniel Hannan's recent post on the subject is worth reading:
'I am a Socialist,' Hitler told Otto Strasser in 1930, 'and a very different kind of Socialist from your rich friend, Count Reventlow'.
No one at the time would have regarded it as a controversial statement. The Nazis could hardly have been more open in their socialism, describing themselves with the same terminology as our own SWP: National Socialist German Workers' Party.
Almost everyone in those days accepted that fascism had emerged from the revolutionary Left. Its militants marched on May Day under red flags. Its leaders stood for collectivism, state control of industry, high tariffs, workers' councils. Around Europe, fascists were convinced that, as Hitler told an enthusiastic Mussolini in 1934, 'capitalism has run its course'.
One of the most stunning achievements of the modern Left is to have created a cultural climate where simply to recite these facts is jarring. History is reinterpreted, and it is taken as axiomatic that fascism must have been Right-wing, the logic seemingly being that Left-wing means compassionate and Right-wing means nasty and fascists were nasty.
 Thatcher at least professed this belief, and regardless of the realities of the Thatcher era, this is what is commonly understood as Thatcherism - the furthest to 'the right' that Conservatives have ventured in recent decades.