The large object had 'landed' on the grass next to City Hall and was emitting smoke and a strange noise.Men in dark glasses were guarding the crash site and refusing to explain to passers-by what was happening.
Potters Fields Park has been hired for a stunt to promote the launch of the Vauxhall Insignia car (sold under the Opel brand outside the UK).
The new cars will be unveiled in the park on Monday.
