Having only seen this word in writing, I assumed it's pronounced "plate". howjsay (whose author is british) suggests the pronunciation that rhymes with "flat", but also offers the "plate" one. This thread, however, has several people who perceive the "plate" pronunciation to be completely wrong.
So how would most people say this in the UK? Is it "plat", and would people in the UK consider the "plate" pronunciation wrong? Does it vary by location within the UK?