At the 1997 G/E, I was involved in the counting and sat 'on the top table' who pulled all the results together from the individual counting teams. At about 2am, one of the jobs we had to do was sit as a large group with a representative from each of the main parties and sift through all the dodgy ballot papers to see if any could be taken as a true vote....ticks in the boxes, a X outside the box, a circle and a tick name next to a name, YES in the box etc. Amazingly, the Tories allowed about 10 votes to stand for Labour and Labour allowed the same number for the Tories on a "I'll scratch your back you scracth mine" basis.
Sadly, the anarchist symbol in a box wasn't allowed to stand.