The original idea of creating a finale that involved performers in the fountains of Trafalgar Square came from Bill Gee of BGA. He invited Avanti Display to devise a spectacular ending for the final Wednesday of ‘Celebration in Trafalgar Square’. This was the last of a series of street art events commissioned by Mayor of London Ken Livingstone – and the final day featured a programme of community choirs and musical acts from London. We would create a show with local performing arts students, a development of our street theatre show The Spurting Man, creating multiple human fountains. Our finale would be twelve minutes long.

My first meeting with the students of Lewisham College was on 20 September, less than two weeks before the performance on 3 October. Using video and photographs of previous shows I attempted to explain what would be required of a 'human fountain'. We had twenty students, which was more than I had expected. Half of them were black and this immediately presented me with a question. The Spurting Man wears skin-tight white lycra and white face make up to look like a statue, but white lycra on black skin has a different effect. We talked about this and agreed that we should have the black performers in black lycra, but that it was an aesthetic rather than a political choice. I had three days to work with the students to develop their roles, rehearse the show and fit the costumes. This looked like an impossible task but I believed that the key to success was a persistently positive attitude. In this situation my most important role was to encourage, giving the group the confidence to take risks.

Day One went well. We kept the energy levels high and didn't bother with coffee breaks. Without pausing to think we rushed from exercise to improvisation. At midday we had a singing workshop with Brenda Rattray, who taught us an African chant. Over lunch the students snatched something to eat while choosing costumes from the college store.

Day Two was always going to be more difficult. The costumes for the human fountains needed to be fitted; I wanted to give the students the opportunity to try the fountain equipment with water, outside, and we needed to rehearse the show.

On Day Three I introduced Mark Parry, a professional performer, into the rehearsal, to play the central role of the Groom. We had not worked together before and I believe that this worked in our favour – having no preconceived ideas of the performance and being aware that he had no time to stop and think, Mark had to go for it, and allow himself to be swept along by the flow of the show.

The Wonderful Wednesday started with my breakfast being cut short by a fire alarm in the hotel. I immediately made my way to Trafalgar Square to meet the delivery of the pumping equipment. The students arrived at noon. We swept the pigeons out of the way and kicked off the rehearsal. Seaming To, the singing bride, was in position at 2pm. Then we ran the show with the music, and for me this was probably the high point of the day. Without costumes, the cast ran through the show perfectly: Seaming's songs sounded beautiful, and the students' mimed water ballet worked perfectly with the music. The tourists loved it.

When at last the cast were all in their hosepipes and lycra, with wedding party coats and hats over the top, their fear was matched by their excitement. Like many partygoers before us, we made our way in an exotic group to Trafalgar Square (having changed in the crypt of St Martin's in the Field). When they saw that the Square was filled with people they faltered, but only for a moment – there was no going back now. I led the group through the crowd, right to the front of the stage. I had given these fledgling performers the task of performing right in the centre of the crowd, to waltz with each other and then with the public to create a celebratory atmosphere in which strangers dance together in the joy of the moment.

As the choir on stage took their leave our Wedding Party took up their song. This was a key moment and they rose to the occasion. Singing pulled the group together, harnessed their excitement and focused their energy – launching their performance into this very public space with a force that swept onwards until the last drop of water had gushed from the pipes. Our Ballet of Trafalgar proved to be a successful climax and, more importantly, the students all enjoyed a uniquely thrilling event, and an opportunity to give a performance in a public space.