Didn't have a long-armed socket set, so was about to give up and pay a mechanic. Fearing a huge bill, I thought I'd have another poke about with a screwdriver. While I was gently probing between the clear plastic cover and the rubber between it and the metal, it just popped off! No broken tabs, no fuss. Bulb pulls straight out. Phew!
Mechanical Incompetant, October 2010