Britain’s police watchdog is to hold an investigation after officers were filmed firing a stun-gun at their own local black race relations adviser who they apparently mistook for a wanted suspect, the force involved said on Friday. Judah Adunbi, 63, who is a founder member of an Independent Advisory Group which works with Avon and Somerset Police in western England to improve relations with the local black community, was shot with the high-voltage Taser gun last Saturday outside his home in Bristol.