First time on this site so pardon any inadvertant faux pas....
I have a 93 750 SS that of course reminded me of the Prince of Darkness at night. I switched to a PIAA 100w (60 watt draw) and ended those spooky nights. I don't know if they sell those bulbs in the UK, but there are a whole slew of them available in even brighter ranges. Another good thing about PIAA is that they last forever and don't seem to put an increased load on the system. Almost ten years in my duck and about that in my Isuzu when I sold it. Hope this may be of some help, but if not, at least we drive on the wrong (vs right) side of the road here in Japan.