Seek coaching, make an effort to speak with a more neutral accent, and try to avoid to sound like a grade school student to attempt to bond with the commoners.
I am unable to understand that after spending several years at an Ivy League university in the UK, he is unable to speak with a more pleasant accent.
If his accent is the Singaporean accent, I believe that we should try to change it. We do not have to speak like the Australians, British, Canadians or Americans, but avoid too much Singlish and poor pronunciation.