When Aston Villa fans invaded the field in the aftermath of their FA Cup victory against West Brom, there followed a torrent of criticism. Descriptions of disgraceful and universal condemnation spread across the media. Fears for public safety and a return to the bad old days of 80s hooliganism proved unfounded though. Some badly chosen back flips and attempted kisses of Fabian Delph didnt earn prosecutions under the Football Offences Act, and the wave of joy built a momentum of positivity culminating in Premier League survival and a Wembley Cup Final appearance against Arsenal. Its important to take action against offenders when things turn nasty, but there are many more examples of fans simply wanting to run around in an eruption of pleasure following the pent-up tension of a massive game. What makes for a memorable pitch invasion? Not just one factor, but a number of them combine to make the viewing fan wish they were there. A large number of supporters all wanting to cover the turf quicker than most of their players did the preceding 90 minutes. An era-defining result for either team helps, but a feeling of total elation and a gradual building of anticipation throughout the game can all result in a great pitch invasion. Alternatively, a totally unexpected action by an unsuspecting animal can prove just as memorable.