This might help, FR.

Flight 26 july 1928:

‘Next to go was Flt.-Lt. Bulman on the Hawker” Heron ” (Bristol ” Jupiter VI “), but unfortunately, whilst taxying up to the starting line, the ” Heron ” ran full tilt into a car standing out on the ‘drome (why, we cannot understand), with serious results to the ” Heron’s ” airscrew and leading edge (and the car).’

There is a photograph of the collision to be seen at https://www.flightglobal.com/pdfarchive/view/1928/1928%20-%200694.html?search=hawker%20heron.