Nothing wrong with Philips bluevision sidelight bulbs! Fully legal.

Anyway, they're not even blue! They give off white light.

Yup the tester probably saw that the bulb itself was blue and assumed a blue light

Just a word of caution, I fitted Phillips Blue Vision W5W side light bulbs and failed the MOT test. The chap who conducted the test said the law is quiet straight forward in that white lights must be shown at the front of a vehicle.

Which is fine as far as it goes but "BlueVision" actually burn whiter than normal 5W bulbs, and since he shouldn't have dismantled the car to see the blued glass...