Ferguson - who has now been made the RIBA's urbanism guru - insisted that Prescott could not afford to ignore the positive effect of an improved public realm.
Speaking at the Centre for European Urbanism Congress in Berlin last weekend, he also claimed that the redesign of some major spaces for security reasons should be seen as an opportunity to improve them.
'It is both an urban and diplomatic issue,' he said. 'I propose that the British and German governments lead the way by cooperating to landscape the street, closed to vehicles by bollards and police vans, to make it a positive pedestrian space that takes advantage of its new traffic-free status - instead of making it look like an impregnable fortress devoid of any humanity or aesthetic quality.
'Security can be turned into a creative design exercise, involving landscape and public art, instead of becoming a reason to brutalise the public realm as has happened so woefully in Grosvenor Square in London around the American Embassy.
'It would be so appropriate for Britain and Germany to cooperate to produce an exemplar for civilised security before the new Berlin American Embassy results in the wrecking of Pariser Platz, which is one of the most poignant public spaces in Europe.
'Unless we do this, we have allowed terrorism to brutalise some of our most precious places without a shot being fired. It may not destroy life - but it does destroy the soul.' Ferguson added.