I'm Rosie from the UK and I'm the great great great grandaughter of Bryan Donkin, the well known engineer. We are cousins :-)
According to the family tree I have, your Bryan Donkin married Margaret Graham (year unknown) and they had three daughters Winifred, Constance and Nancy. Bryan W Donkin was the son of Bryan Donkin and Emma Day. Their parents were my great great great grandparents: Bryan Donkin and Mary Brames.