This was a day that was supposed to be about a loud but peaceful protest. Fans turned up with banners, some pushed children in prams, disabled protesters attended in wheelchairs. However, within a couple of crazy hours, supporters were running around Old Trafford offices, destroying pitchside camera equipment and even carrying off a corner flag.
Standing among them, it quickly became apparent that the afternoon had the potential to turn ugly.
The sight of an air ambulance from Royal Blackburn Hospital landing in an Old Trafford car park when the protests were reaching their height was a particularly worrying sign.
Paramedics had been called to treat an elderly fan who had fallen and suffered a head injury, but while that incident was the result of an accident, there were other, more sinister aspects to the day’s events.
Supporters had begun gathering in large numbers around 1.30pm. As the sun came out, so did more fans, armed with flares that filled the air with red, yellow and green smoke.
Souvenir sellers did brisk business in gold and green scarves - the colours of the original protest against the Glazer family’s controversial purchase of Manchester United in 2005 – and a local supermarket an even brisker one in cans and bottles of beer.
Organisers handed out placards promoting the “50+1” model of fan ownership that supporters groups in England have begun to champion in the wake of the failed move to launch a European Super League by United and five other English clubs.
Numerous banners hung from railings and were carried on poles, bearing slogans of varying sophistication but all bearing one very simple message: Glazers out.
Police were plentiful, but low key, and when a group now totalling 2,000-3,000 fans moved from their meeting point outside the Old Trafford superstore towards the Munich tunnel and memorial clock, stewards hastily removed a barricade of plastic barriers, presumably to avoid supporters being injured.
That, however, gave fans access to the turnstiles and exit doors in the disabled section of the stadium, with a number gaining entry to the ground via door AE8 just after 2pm.
Then, as images appeared on social media of fans inside, the mood outside became even more animated, with people leaping onto vantage points to unfurl more banners and let off even more flares.
A metal barrier had been drawn across the entrance to the Munich tunnel, denying access to the entrance to the directors’ box and, further along, the dressing room.
But with fans inside the ground, that hardly mattered. At one point, a handful appeared at a window, having breached a corridor that leads to the boardroom, and waved to supporters outside, to raucous cheers.
By 4.15pm, however, the mood had turned ugly, a point at which the police began their swift, and successful, effort to disperse the crowd and finally cordon off any access to the stadium, although two officers were injured in the scuffles that ensued.