Independent Catholic News are carrying two reports of this debate, held at the invitation of the Central London Humanist Group and the British Humanist Association. The first is a report by Jo Siedlecka and the second a text of the speech given during the debate by Fr Christopher Jamieson.
From all appearances, this looks to have been a very useful engagement by Catholic Voices on behalf of the Catholic Church and the forthcoming visit of Pope Benedict XVI.
UPDATE: There is more coverage of this debate here. This coverage suggests that it took quite a bit of courage for those supportive of the Papal visit, and of the Catholic Church in general, to express their views. "Bear pit" is the descriptor used.