When I went to Trafalgar Square just last week to witness London winning the Olympic Bid 2012 I encountered joy, happiness and excitement.
The contrast to what Trafalgar Square looked like yesterday evening could not have been any starker.
Instead of tears of joy people shed tears of sorrow. What struck me most was seeing London's mayor Ken Livingstone wiping his eyes with a tissue backstage right after he had made his speech. He must be devastated. I caught him having a refreshment after making his speech in the scorching sun to thousands of people.
Next to Ken there were speakers of different faiths, together with celebrities, such as newsreader Sir Trevor McDonald, calling Londoners to stay strong together, regardless their faith or ethnicity.
Everybody listened in silence, clapping every few seconds in agreement with statements of encouragement.
TV crews and photographers were running in between the crowd, stopping to interview and photograph the spectators.
Many had brought their own banners and posters. Others were holding white balloons as a sign of sorrow.
It was a touching an memorable event. Seeing thousands of Londoners shoulder to shoulder certainly proves that they stand united against the threats.