Meh. Pretty lousy for a Naschy film. The story is convoluted and hard to follow. Without any scares, and music that is completely mismatched, it's hard to recommend. There is some gorgeous cinematography though...

A double dose of Nashi as he plays an Indian holy man battling his evil, twin brother's Voodoo-raised zombies in swinging London. Chaos ensues.

There's an English dubbed version on the Internet Archive: https://archive.org/details/Vengence_of_the_Zombies