w00t?
You need an earlier PoD than 1946 to get that. Ever since the social democrats and the socialist/communists broke apart in 1917 over the revolution issue the social democrats have been anti-communist. At all positions they outmanouvred the communists - the 1928 'cossack election' did not polarise them, instead they capitalised on Ådalen 1931, rendering the communists completely irrelevant, despite the fact that the strike and demonstration were communist affairs from the beginning. The communists started splintering early too, losing influence.
This made the social democrats acceptable to the traditional "white" classes - small land-holding farmers, the industrial elite and the nobility - sure, they were annoying, but so much better than the communists and they were keeping the communists down.
To have Sweden turn Tatcherite, you need the social democrats to be weak (both to be unable to hold the communists down and to take and keep power themselves) and the communists far stronger, to have a reaction against the communists in form of a Tatcherite party.