SNP letters advising members of long-standing they are suspended from office pending removal of membership

In the past 2 weeks, I have been advised by 7 SNP officeholders/members of long-standing that they were in receipt of a letter from a more senior party official advising their suspension from official duties and any party political activity pending investigation of their behaviour and possible dismissal from the Party. I viewed four of the letters and the content of each is very blunt and very similar.

But how many more letters are in existence or in the pipeline?

Is there a Stalinist doctrine purge underway or is the spectre of McCarthyism on the horizon?