I live under a virtual rock, media wise...So I don't know if a link to this British documentary has been posted before. The main focus is on water speed records, but there is plenty of film footage about the family's land speed record attempts from the 30's through to the mid 50's. Its about an hour long. http://watch32.is/movie/zGWge7GP-donald-campbell-speed-king.html
A late friend of mine was in the team of divers that recovered the Bluebird from Lake Coniston where the speed water attempt took place. There is some amazing film footage of the land and water attempts well worth a look at, if you can. Pioneers.