"Mortimer" writes:

It's quite right that they don't count vehicles going through on amber
because this is not actually an offence. The whole point of having an

TSRGD 2002 para 36

(a) subject to sub-paragraph (b) and, where the red signal is shown at
the same time as the green arrow signal, to sub-paragraphs (f) and (g),
the red signal shall convey the prohibition that vehicular traffic shall
not proceed beyond the stop line;

[...]

(e) the amber signal shall, when shown alone, convey the same
prohibition as the red signal, except that, as respects any vehicle
which is so close to the stop line that it cannot safely be stopped
without proceeding beyond the stop line, it shall convey the same
indication as the green signal or green arrow signal which was shown
immediately before it;

Seems pretty clear cut to me. Unless the vehicle is too close to be
stopped safely, it's the same offence as going through on red.

http://www.opsi.gov.uk/si/si2002/20023113.htm#36


-dan