Complex sentence: Jack Corbett, who met him in 1947 during a trip to London to examine British deception in the post-war era, found Wild to be a reluctant collaborator and although he was "cordial, and socially friendly" described him as "a slippery customer".
Split into simpler sentences: Jack Corbett, who met him in 1947 during a trip to London to examine British deception in the post-war era, found Wild to be a reluctant collaborator. Although Corbett opined that Wild was "cordial and socially friendly", he described him as "a slippery customer".