Okay well I'm feeling that the general consensus is a no then!
It's not a big issue, I have been riding 12 years with no hazards to use and not had a problem, as I said I just feel anything that might catch eyes of a driver using their mirrors can only be useful, but would not want to be on the wrong side of the law.
Retraite, I admit that it was about 6 years ago but I drove through Holland to Germany and back and practically every bike we saw filtering was using hazards, particularly when we were coming out of Amsterdam at rush hour and it was rather busy.
Mitch, that is interesting that you were told to use them - how long ago was this?