Original sentence: David Myatt has always denied such allegations about involvement with the ONA, and using the pseudonym Anton Long, and has  challenged his accusers to provide evidence of such allegations, which he has claimed they have failed to do
Edited sentence: David Myatt has always denied such allegations about involvement with the ONA, and using the pseudonym Anton Long, and has repeatedly challenged his accusers to provide evidence of such allegations, which so far they have failed to do