I never looked at the winning margins behind the conservative victory, but after the wholescale election fraud in US to topple Trump, facilitating coronavirus as smokescreen to do so, I can believe the UK general election was rigged too to topple Corbyn, both in their own ways deemed enemies of the deep state.
But this would rest on an examination of the postal votes. Is it true counting machines were used, and if so could votes be distributed to marginal constituencies to provide small winning margins, which is all that’s need in a FPTP system. However if counting machines weren’t used I’m not sure how the election could be rigged, as counting paper ballots by hand with observers is mostly secure.