This link shows that someone complained that the word 'Sambo' was used;I believe that the previous word was 'Coon'.
https://www.ofcom.org.uk/about-ofcom...cast-bulletins
This link explains why black people find these words offensive:
https://ferris.edu/jimcrow/coon/
In my younger days I remember people using the word 'sambo', but not 'coon'. It's telling that these terms have fallen out of use as the man charged with reviewing content before it was broadcast didn't flag them up as potentially offensive because he'd never heard of them!