The requirement is specified at
http://www.hmso.gov.uk/si/si1989/Uks...n_9.htm#(4i)i2
See paragraph 12(b).

I wonder what that figure of 1.3% actually *means*. It's a strange way to
specify what is really an angle between the horizontal and the beam. I
presume that 1.3% equates to arctan(1.3/100) or 0.75 degrees. I suppose it's
done like that because the easiest way to check the setting is to position
that vehicle a known distance (eg 10 metres) from a vertical wall and
measure the vertical offset (eg 1.3% of 10 = 0.13 metres) of the beam from
the straight-ahead position of the headlamp.

Excellent - Thanks

And if your'e wondering what kind of obssesive mind you need to think
of theses thing:

Bi weekly I meet a mate and we go to a Jam night in a pub. QED no
driving as beers are consumed. Once the 1.3 % sign had been noticed
once, well that was it.
--
Klaatu

Gort! Deglet Ovrosco!